I hate cars

It's perfectly fine under the right conditions. Look at many cars that are sold in both North America and Europe. Many cars that spec a 20wt over here where CAFE dominates spec a 30-40wt over there where CAFE does not interfere and lowest wear is the goal. I wouldn't blindly put a thick oil in the car but if you live in a warm area and you're going to be heating the oil more than normal, go thicker. Typically raising the oil temp 20 degrees will make it one grade thinner.

Clean is good but is not a matter of viscosity, only the additive pack and in the case of an ester oil, the base oil.

Modern oil is great.

You have to understand any information that makes it to a video intended for the general public has gone through many hands to be approved. You're not getting what's in your best interests or even what an engineer would suggest for lowest wear, you're getting the watered down crap that they have to say thanks to CAFE. If I had a 300k a year job as a lead chemist and they told me to say thinner is better I would probably say thinner is better. I'm going to watch the video this time and comment on it.

This goes back to the above, why would you believe anything you read when the marketing and government has their hands in it? The manufacturer does know what's best but that doesn't mean you're getting that info. Does Honda know more about their engines than I do, yep. Does Honda have the absolute lowest wear in mind, nope. They compromise due to government interference. But that's where an understanding of what's going on is handy. We, as the individual can adjust and use what's best for us instead of blindly following the marketing department.

As for clearances and tolerances and journal bearing diameter and all of that stuff, it can be found in a rebuild manual and there are no differences within the J32 from when the switched from the 5w-30 to the 5w-20. No internal changes, look for yourself. Even something like rod bearing side clearance which can be tightened up to help boost oil pressure with a thinner oil remained the same. Nothing internally changed. As I said one of the best engine builders on this forum noticed the lack of oil pressure at hot idle. It's not the end of the world, my turbo car used to run 1-2psi at idle but it's still not great for lowest wear. The thinner stuff will allow more wear, you have to decide if the tradeoff of .5mpg or less is worth it to you.

I have been lucky enough to see these tests done by Ford and it's not pretty. The engines still last long enough on the 20wt, 200,000 miles or more but after their identical drive cycles on a 20wt and 30wt and sometimes a 40wt, the difference in wear when torn down is enough to make anyone stay away from the 20wt even though the engine will still last on a 20wt.

I've used a 0w-20 before, back when I was in Flagstaff and it was 12-17F each morning and I drove under 2 miles each way. In that scenario a 0w-20 is perfect. I would have used a 0w-10 if it were available. The stop start engines typically used in hybrids benefit from a 0w-20 since they run low oil temps. There is a use for 0w-20 oils but its not for the typical TL owner in a normal climate that drive more than a few miles at a time if you want the absolute lowest wear.

One thing to clear up though, there's no difference in time to full oil pressure during start-up as long as you use the appropriate viscosity for your climate. A 40wt will get "there" just as quick as a 20wt. Oil pumps are positive displacement, they pump the same volume per revolution no matter what oil is in there, only the pressure changes, it requires more pressure to pump the thicker oil at the same volume so you see an increase in oil pressure. As long as the bypass doesn't open you're fine. The crank will float in the main bearings by rotation alone, it doesn't require pressure for the first couple revolutions. Cam lobes are usually bathed in an oil bath so they have lube instantly on start-up. Unless the engine has sat up for 20 years, the cylinders have lube on start-up. A 40wt will get to the same areas and it will get there just as quickly upon start up. As long as you use your brain you will have no problems. Use a 60wt in a cold winter and you'll have problems but I doubt anyone would try that.


They do. They know the engines will last reasonably long with the 20wt so they can get away with it. They know most people buy these cars to get from point a to point b. But again if lowest wear is your goal, you're losing nothing by going to a 5w-30. Look at the turbo engines. They still spec a 5w-30 because they make more power per cylinder and the oil will run hotter. That brings me to climate, you don't just spec one oil for all climates. Maybe once VI gets well over 200 that might be possible. But you can't tell me a 20wt is best for a Phoenix summer and for an Alaska winter. A 40wt in a Phoenix summer will be thinner at full operating temp than a 20wt in an Alaska winter, something to think about. So if a 20wt is acceptable in cold climates, show me why a 40wt is not acceptable in a hot climate where it will still be thinner on average. Answer this one question and I'll be done.

All I ask is for people to use common sense instead of blindly following Acura's marketing propaganda. Look at what happens to viscosity as temperature changes, read up on HTHS, look in a service manual to prove for yourselves that no changes were made when they went to a 20wt. Most importantly look at the kickbacks manufacturers get for back specing their older engines to the thinner oil. Look at the penalties they have to pay if the oil filler cap does not way 20wt. You might have to purchase the SAE papers to find this info but it's there. It will give some insight into why everyone has switched to the thinner oils and it's not for our own good, it's for the corporate average fuel economy. Hasn't anyone ever wondered why manufacturers have started backspecing old cars that are no longer sold to a thinner oil? It's additional money out of their pockets to do this and I promise you it's not because they care about the environment.

4drviper

@ ^ last quote

so honda kinda knows "too much" that 5W20 is "fine" but optimally 5W30 is what's supposed to be in the crankcase

Bruce Banner

iTrader: (2)

Manufacturers will tell you "truths", they say it's fine, but they don't elude to specifically what it is fine for. How long a manufacturer defines the life of a car is not the same as an owner. Their fine may be for an engine of expected wear for 8yrs, because they expect you to buy a new car by then or even 4, cause a new body style will come out so that generation is done. For an owner, you might plan to keep it for much longer.
bottom line here is, run what you feel is good. 5W30 is usually easier to find in qty and price.

nfnsquared

Well, in the video Jetter was pretty specific:

"We have absolutely no concern whatsoever with wear with 0W20..."

And don't forget, Honda/Acura has been running 0W20 for 12 years now in Europe and Japan. I have 9 years and 130K miles on 5W20 with zero issues.

nfnsquared

Do you have a link for the above claim (I assume allegedly made by Paul?) that stock J32's have "scary low oil pressure" at idle when running 5W20?

I do know that Paul claimed low oil pressure (7-9psi) on a built J35:

"Syn oil seems to thin out alot more that conventional with heat. A example of this was with Kschwiggy's car, he has a AEM oil pressure gauge and a built J35. With Mobil 1 5W20 at full operating temp at Idle he was only getting 7psi of oil pressure, now the same engine with Castrol 10W-30 again at full temp at idle was getting 15-17PSI. The factory spec for these engines is 10PSI minimum although I like the 15+ PSI much better, now this lack of pressure means that oil is not providing great protection for the bearings, but more imortantly as in Kevin's case, was not producing a good oil layer on the cylinder walls, this oil is squirted on by small jets on the ends of the connecting rods, without sufficent pressure a incomplete layer of oil will be put on the sleeves and they will eventually wear out (as was seen in Kevin's engine when we swapped his heads). Now before everyone points out the weight difference in the oil, 5W-20 Castrol was also put into this engine and got to 10-12PSI, but again I prefer the higher pressure."

http://www.bobistheoilguy.com/forums...51&nt=3&page=1

I hate cars

I don't know why the multi quote isn't working, I hope I don't piss off Mr Bell.

As I've said, the engine isn't going to blow up or wear out inside of 100,000 miles on a 20wt. On the flip side of your argument there are many of these engines running 5w-30 with well over 200,000 miles so instead of me always trying to prove to you that a 30wt is better for the lowest possible wear, why don't you show me how a 30wt is worse for wear than a 20wt.

A 5w-20 will have a higher HTHS on average than a 0w-20. A higher viscosity index is a good thing. If you can find a good 0w-20 such as Redline with a much higher than average HTHS I would run it over a 5w-20 but in most cases a 0w costs you precious HTHS value.

I'm sure the Honda marketing department has "no concerns" with a 0w-20 because odds are it's going to make it out of the warranty period easily on that oil.

Again, what I want people to know is WHY manufacturers are switching to 20wt oils so they can make their own educated decisions as to what's best for them based on their priorities and driving conditions. I want people to read between the lines and if they still choose a 0w-20, that's fine.

The one thing that is an absolute, the engine will wear quicker with the thinner oil. That could still mean 250,000 miles, who knows, but it will wear quicker and that's where personal preference comes in. Most European manufacturers actually spec an oil based on the HTHS value because cars are expected to be driven hard over there.

Many of the Japanese engines run on the thin stuff are start stop engines and very low hp engines. Also take into account the climate in Japan. It rarely gets past 88F in the summer and the average temperature is 59F. That's quite a difference than those of us in Vegas, Phoenix, Bakersfield, and many other places where that 20wt is now a 5w or 10w when it's 30-50 degrees hotter at full operating temp.

Bruce Banner

iTrader: (2)

That's the kind of half truth I'm talking about. Those are the kinda of open ended statements that any public speaker makes to allow people to infer. You can't bust them for lying cause they didn't. It's saying the car drives well..... sure it drives well, but I didn't mention that under certain circumstances it won't. So when a person runs into those circumstances, the statement wasn't wrong, it didn't address that scenario.

This thread will go on forever, to each their own, use what you want for personal peace of mind.
A mod should probably just close this thread, it's not going to go anywhere.

I hate cars

Agreed. Most important in the statement you quoted is its been used successfully in Japan for years which is substantially cooler than most of America in the summer. That 20wt can literally be one full grade thinner in our summers making it a 10w.

tudtran

This is lots of good info. I guess the only way to know is to try it out for myself.

Grand_hustle17

whoops, just bought 10w30 synthetic lol... will be returning

I hate cars

Nothing wrong with that weight as long as you don't live in Alaska. I ran a 10w-30 for 70k miles year round. It rarely gets below freezing here and summers are in the 90s up to 110F. You won't hurt a thing. In fact it can be better in some ways. What brand did you get and what's your climate like?

Since Redline changed something with their formulation and the 5-30 has a slightly lowered HTHS of 3.7 which is still extremely high for a 30wt it gives me an excuse to make a change. Ill be running the 0w-40 next time I change the oil. I posted in another thread but while the 0-40 is heavier at full temp (212F) and a little thicker still at 100F by 68F its the same viscosity as a 10w-30 and around 59 its very close to the 5w-30 and thinner than the 10w-30. At freezing the 5w-30 and 0w-40 are almost identical and by 20F the 0w-40 is finally thinner than the 5w-30.

So basically I will be running a thicker oil when fully hot but about the same viscosity as what I currently run during a winter cold start. HTHSv is 4.0 vs 3.7. 3.7 is very high and I really shouldn't be worried about the difference, that's me being OCD. If it were the difference in a 2.8 vs 3.1 I would be a lot more happy but at least I have an oil that I can beat the living crap out of and there's no way to come close to stressing the oil. I can run it down the freeway in 2nd gear or overheat the engine or track it everyday without changing the oil in between and I couldn't hurt it. Zinc and Phosphorus and Moly levels are about the same between the two.

I usually don't like the large spread between numbers but there can't be much viscosity index improver with an HTHSv of 4.0. I reason the change because its no thicker when cold, thinner when really cold, thicker when hot with a viscosity index of 200 and about the same awesome add pack as the current oil.

One other reason is I do a lot of idling. Like hours sometimes and I want a thicker oil for the sustsined low speed operation. Higher viscosity is a good thing in a journal bearing in low speed operation.

Any thoughts, comments? Experiences with a 40wt in the TL.

Grand_hustle17

Temps in the summer is like 85-100* here

Huskymaniac

New guy here. I have to say that IHC knows his stuff. HTHS and viscosity under your particular conditions are what matters. Also, Redline is the best.

I have been driving Subarus for many years now. This is my first Honda product and I have to say I was shocked to see that they specified a 20W oil! In Europe, there is a certification/standard that requires an HTHS of 3.5. HTHS matters for the reasons that IHC mentioned numerous times, it reduces bearing and other wear at operating temperatures and high stress (RPMs and throttle) conditions. For my SVX, people were losing bearings left and right when they were running 5W30 M1 15 years ago. It simply wasn't thick enough at operating temperature. The bearings were made with tight tolerances and it was difficult to maintain a film on them. The Germans, for all their faults, know this as well. That is why the HTHS is specified at a minimum of 3.5. Since I bought my SVX I have been running a blend of M1 5W30 HM and M1 0W40. The blend gives me an HTHS of exactly 3.5 while still remaining nice and thin at upstate NY winter temperatures.

When I saw the Honda specification of 0W20 I wondered if there was something else about the engine that required such a freakishly thin oil which has ZERO chance of getting an HTHS rating of 3.5. Maybe the passages are tight and the pressure gets too high? Buying the extra 0.5 MPG for CAFE tests makes sense but I have to ask, is there anything else that causes the engine to require 0W20? If not, I am going to stick with my 3.5 HTHS goal in choosing the oil for this car.

For those that wonder why I went with M1 HM versus Redline, I am cheap. I had planned to run 6K between changes using an oversized Purolator P1 filter. That was too frequent to justify the cost of Redline. Now, if I am going to be going to more like 7500-10,000 miles with this car, I may consider Redline. I like the idea of using the MID. If that is going to go off that infrequently, the benefits of Redline start to outweigh the costs.

I use Redline everywhere else in every car I have except for brake fluid which is either MOTUL or ATE.

nfnsquared

Interesting question/concern, especially since these engines were designed for 0W20 and a corresponding HTHS of 2.6-2.7 (since 2001 IIRC).

I ran M1 0W40 (HTHS of 3.7 at the time) for one change and had disturbingly elevated iron levels (avg increase of 39%, adjusted for mileage) compared to the before and after intervals using 5W20 oil.

If you switch to an HTHS of 3.5, I hope you run a UOA on the drain before you add the 3.5 oil and then again on the 3.5 drain. It would be interesting to compare and see if you also get elevated iron levels with the higher HTHS oil...

FYI, here's the numbers:

Before: M1 5W20, 8198 miles, iron=17 (TBN=2.1)
M1 0W40: 10,868 miles, iron=32 (TBN=2.0)
After: Honda 5W20, 7400 miles, iron=16 (TBN=1.3)

Edit: Purolator Pure One filter used on all 3 intervals.

Huskymaniac

Do you have a picture of the UOA you could post? What company did you go with for this? I did one once with the my SVX and the UOA was fantastic with the oil blend I chose. I wonder if the 0W40 didn't have iron in it to start. I will see if I can find a VOA on that oil. I can't imagine why a higher HTHS would cause high iron but not high chromium or copper as well.

I hate cars

Dead wrong. I've told you time and time again that UOAs can not be used to determine engine wear. The wear metals portion of the test is invalid. Also, these engines weren't "designed" to use a 0-20. They originally ran a 5w-30 and 10w-30 and the oil weight was gradually reduced to meet government standards with no changes the the engine. Not the clearances and not the oil pump.

Back to wear metals... Oxidation shows up as wear metals in the flawed spectro tests. So if the oil cleans well as Mobil One 0w-40 does you see higher wear metals, specifically iron.

On top of that, the test can only "see" very small particles. The larger particles that are a result excessive wear go unnoticed. I've had an engine give me sparkly oil and the UOA was fine. The engine destroyed itself in 2,000 miles yet UOAs were ok.

The only way to get a real indication of what's going on besides a teardown is a particle count. It costs more than $20 so I doubt you're going to use it. There is overwhelming evidence and laboratory tests to show that a higher HTHS reduces wear. Arguing that a higher HTHS increases wear is like arguing that water is the best lubricant.

Redline is another oil that will show high wear metals especially when it's first put in I've had pretty bad wear metals on my turbo car which worried me but even at 200hp/liter and 80,000 miles upon teardown it looked new and spec'd new. I blueprinted this engine so it was extraordinarily easy to compare the before and after and there was virtually zero wear even though UOAs were less than great.

UOAs are fine for determining oil change intervals, showing coolant in the oil, TBN, TAN, oxidation, etc. They are not good at and should not be used to determine wear and the wear metals should be ignored.

For once, research something. Think out of the box. Question the test method when it doesn't match the expected results. If you search hard enough you will find particle count vs spectro tests and it might open your eyes.

nfnsquared

Huskymaniac,

I'll continue in a dialogue with you. Sorry for the other individual who can't seem to enter into a civil discussion.

There is no iron in M1 0W40 that I could find. That's the first thing I checked when I got the UOA back. Copper was also elevated, but not by as high a percentage. Chromium was unchanged.

I had used M1 5W20 exclusively (100,000 miles and 7 oil changes) up until the M1 0W40 change, so really doubt any excess iron is due to "cleaning".

I have always used Blackstone Labs. With TBN, the cost is $35 ($10 extra for the TBN). I'm very interested to see if the elevated iron results are duplicated in another J32 running high HTHS oil. If you choose to run a high HTHS oil, I hope you'll run back to back UOA's for comparison.

M1 0W40 voa's:

http://www.bobistheoilguy.com/forums...Number=1722539

http://www.bobistheoilguy.com/forums...Number=2365762

And here are the UOAs for comparison:

Huskymaniac

I have no idea where in the OCI the car I am buying is but I know I was going to wait until at least my second oil change to do a UOA for the very reason you mentioned. The first one can be a cleaning phase and throw bad results.

Why did you settle on 0W40? I looked at the RL oils yesterday and I was thinking something like 2 parts 0W30 and 2.5 parts 5W30. That would give me good viscosity at our lowest temperatures of -20F in the bad winters and an HTHS of about 3.5.

I also started looking at oil filters. I generally go with Purolator Pure One but I am concerned about using that for extended OCIs. I see that people generally use one of two filters. I will refer to them by their purolator numbers of 14459 (short and fat) and 14610 (long and skinny). There is evidence that they actually have the same surface area and capacity. Th 14459, which some people refer to as "oversized", has a lower bypass pressure of 12-15psi versus the 14610 of 14-18psi. That alone makes me think we should stick to 14610 and equivalents as these meet the manufacturer's specification for bypass pressure. As to which filter specifically to use, I found the Purolator PSL14610 and the Royal Purple 10-2867. They have similar filtering and flow resistance specs. I don't know exactly what synthetic material purolator uses in their but the name "micro-glass" used by RP scares me a little. If it really is glass (silica) it would be quite abrasive if little bits and pieces broke off and got into the oil and, subsequently, into the engine. But I haven't seen any evidence out there of this becoming a problem.

What are your thoughts on the oil and filter choices?

Huskymaniac

That post above is for IHC...sorry for any confusion.

maharajamd

iTrader: (1)

^Lol ouch

I hate cars

The glass referred to in the filters is a glass fiber. It's not very abrasive as its name would imply. The benefit to this media is better flow and better filtration along with more consistent pore size. The fibers themselves are smaller than the traditional cellulose fibers so you end up with smaller pores between fibers for better filtration and more pores for better flow. I've always used RP filters with Redline oil. The main reason I use the RP filters is because of the media but if Purolator now has a synthetic media filter I'm sure it will work well. Other things the RP filter offers that you might want to check especially if you plan to do extended drain intervals is a silicone anti drainback valve and wire reinforced media with metal end caps.

The filters bypass opening psi is based more on what the filter can withstand than anything to do with the engine. The bypass is there to protect the filter. Since the oil pump is a positive displacement pump its going to pump the same volume of oil regardless of pressure. The higher the rating the less chance of unfiltered oil getting past the filter. In reality, pressure drop through a synthetic media is only going to be 1-2psi. I've seen cold engines with cold oil at high rpm have just 8psi of differential pressure. Regardless of the rating its not likely you will ever see more than a few psi of pressure drop across the filter unless you run a thick oil and like to go racing on a stone cold engine lol.

A larger filter (assuming it has more media surface area) can usually get away with a lower bypass opening pressure. Same with a synthetic media since it offers less restriction. On the flip side, the syn media can withstand higher pressures too.

I need to change my signature. I'm running Redline 5w-30. The other oil was an experiment. Their 5w-30 is loaded with ZDDP and moly and has a HTHSv as high as most 40wts. There's really no need to go with any more or any less unless you live in a very, very cold climate. Mixing is a good idea to get the properties you want. I can't remember off the top of my head but I found a mixture of redline oils that will give a high viscosity index and high HTHSv

Sorry, got to cut it short, something just came up at work.

maharajamd

iTrader: (1)

Cut it short? D:

Huskymaniac

IHC,

The new Purolator filter is supposedly very similar to the RP filter including metal backing and silicone check valve. They are also, no surprise, nearly identical in price. At this point, I think the RP is actually easier to find.

The blend you are probably referring to is something like 2.5 parts 0W40 and 2 parts 0W20. That gives an HTHS of just over 3.5 with a VI of 182, roughly. Let's call it a 0W35!

I hate cars

Sounds good to me.

What is this new Purolator called? I might try it out next time.

Huskymaniac

They go by PSL14459 or PSL14610.

94eg!

IHC....I'm stuck with an oil dilemma right now. I'm currently using Mobil 1 HM 5w30 in my 220k mile CRX. Car runs great but burns a little oil (3/4 quart in a year). I'm due for an oil change and am thinking of going with Redline 5w30 instead (like all my other cars). In your opinion do you think it's worth the extra cost ($23 5qt vs $44 4qt) or even a good idea on a high mileage engine?

I looked at VOA's on both oils and the Redline seems to have more of pretty much everything. Especially the anti-wear additives. Plus the blah blah about Ester's is supposed to be good. But I'm not quite sure about eliminating advertised "seal conditioners" in the M1 (whatever that means). This car has been running M1HM ever since it came out, and the outside is dry as a bone (new pan gasket and cam seal).

I guess I'm just looking for that extra reason to push me over the edge.

I hate cars

I did a search to get a price for this filter and couldn't help but click on a BITOG link. Now I don't put much weight into what anyone says over there but they presented some pretty damning facts about the Purolator synthetic filters along with pictures. It looks like the media did not hold up well, might have even ripped. There was also overspray of the grippy stuff into the filter itself. That is just one person so who knows if they're all like that. I'll probably buy a couple at least to cut open anyway.

http://www.bobistheoilguy.com/forums...Number=2684181

I guess it's back to RP.

I probably mentioned it somewhere but Amsoil's EAO filters are of very high quality and use the same media. Those were my first venture into synthetic media filters. The one bad thing I noticed is the oil pressure light took just a little longer to go out with the EAO filters of the same size. It was barely noticeable but it was consistent. Using the RP filters of the same size results in the oil pressure light going off just about instantly. I can only guess the RP filters have a better anti-drainback valve which is fairly important on these engines since you have a pretty good column of oil above the filter.

94eg!

No love for me?

I hate cars

Oh wow, sorry. I did not see that. You know as much as I do about oil. The HM oil is so good, I'm not sure Redline would make a difference. The two items I've found that seem to make a difference with oil burning is HTHSv and NOACK. I believe Redline is better on both of those specs but probably not a lot better.

It's definitely worth a try, at least for one OCI to see if it does anything. If it reduces or eliminates the burning that would be great but the one downside of an ester oil is the deposits they leave behind are pretty bad. They will never leave any deposits during normal operation which is what makes them good but in the combustion chamber if it's being burned it's something to think about. Plus the additional zinc, phosphorus, and moly will all leave more deposits if it's burning oil too. Definitely worth a try but if it doesn't stop the burning or at least come really close I would go back to the M1 HM oil.

Just re-read and saw that you're only burning 3/4 quart a year. Do the Redline.

The seals can be tricky. If you've been using an oil with a lot of seal conditioner (seal swelling agents), sometimes you're stuck with it. Reducing or eliminating the amount can make the seals shrink and cause leaks. The good part is it can usually be cured by going back to the higher seal swelling agent. Esters are nice to seals so generally they don't use as much seal conditioners.

Other than that stuff, you know the usual benefits, high HTHS, low NOACK, great additive package, no deposits very polar, etc.

94eg!

Good food for thought. Guess I'll go for it and just keep an eye on it. Right now the M1HM has run for 14 months and only 2.9k miles. I split my daily driving between 3 cars so mileage is not a factor. At least it gets driven regularly (at least once or twice a week average).

Huskymaniac

Hey, I hope you are still monitoring this thread. I spoke with my mechanic when I drove in to show him the new-used car. He mentioned that he had been told that the VVT requires a certain weight oil to work properly. Ever hear of this? Believe it? If so, what is the acceptable weight range?

Huskymaniac

On a related note, has anyone replaced their differential oil? I see transmission fluid on the list of maintenance items but not differential fluid. I also don't see brake fluid.

nfnsquared

No to DF. Brake fluid is every 3 years. It's in the OM (under the Maintenance section) and also in the SM.

I hate cars

I'm still here. To answer your earlier question, viscosity has little to no effect on any form of variable valve timing, that's a myth. I've been working up some numbers with different SAE weights at different temps and why the use of 20wt in every climate is very flawed. I'll hopefully post them this afternoon.

Our differential shares fluid with the trans so when you swap out the tans fluid you are swapping the diff fluid too.

Brake fluid should be done at your own discretion. From the moment the bottle is opened, moisture starts getting into the fluid and the boiling point drops from that moment on. Humid areas tend to collect moisture in the system quicker than dry areas. Driving style plays a large role. If the fluid never sees temps greater than 200F from easy driving you can go longer without changing it. If you're pushing the fluid temps up higher from aggressive driving you won't be able to tolerate as much moisture and it should be changed more often.

I look at dry and wet boiling points like everyone else but I put more emphasis on the wet boiling point because I think that's more representative of real world conditions, especially after being run for a year or two. It's kind of expensive but I like the Motul RBF600 due to its higher than normal wet boiling point. I swap this every 2 years. Back when I would track the car I changed it once a year. Now that it never sees the track and the BBK has lowered fluid temps, 2 years is playing it safe.

One other thing to think about is all of the rear calipers that have been sticking. Just about everyone who has had this problem has reported rust and moisture in the caliper. Whether this is a low spot and a natural catch area for moisture or whether its getting into the caliper from the caliper I don't know. But I would think one way to prevent a seized caliper is to flush the system more often before the moisture level can get to the point of causing problems.

Huskymaniac

That's funny. You and I are on the same wavelength with fluids. I just switched my other cars over to Motul RBF600 as well. Just to be clear, does the limited slip front diff on the 6MT share the fluid with the transmission or is that the case with the AT?

On my Subaru SVX the center diff shares the AT fluid but the front and rear diffs do not. The front diff is open on that car and the rear is viscous limited slip and both use gear oil. The center diff is a clutch style diff controlled by the TCU.

94eg!

Yes it does. The ATB style LSD Honda uses do not require special fluids to function. In fact, Honda used to spec standard 10w30 or 5w30 motor oil as it's gearbox fluid before they came out with their own custom MTF in the late 90's. In all that time, the design of their LSD's has not changed.




It's literally just the force exerted by the diff housing trying to accelerate the internals that puts the brakes on diff action. The gear teeth are being smashed against the walls of the housing (as shown in the bottom left fig.1 of the above image). As you can see in the below image, the gear teeth have a flat friction surface on their outer most radius that gets forced against the walls of the diff when you accelerate:

94eg!

I forgot to mention there is also thrusting of the internal gears that adds additional brake force to the diff when accelerating as shown in fig.2.

TLer trash

I've read on tech forums (iatn, especially) that some of the "displacement on demand" engines can be especially viscosity sensitive. It seems to be a bigger problem with some chrysler products.

I hate cars

I've got to get the numbers together. Those systems are not viscosity dependent. If they were, those sold in cold climates would not function where that 20wt is now a 40wt at full operating temp. They would be extremely sensitive to temperature if that were true including light load operation.

TLer trash

Makes sense to me; wouldn't be the first bs I've heard from dealer techs or oe mfgrs.