Ok, I know I'm setting myself up for endless frustration and I should learn from my past ATF threads but I want to document and have a time stamp on this switch.

So, a little history, bought the car new in 12/05. Went approximately 20k which was under a year on the factory fill Z1 until I checked it one day and it was black. I know color doesn't always mean a whole lot but this was thick and black and just nasty. I filled it with Amsoil "ATF". Went about 5k and filled with Amsoil "ATD". It supposedly has a little less FM and is a little more robust than their normal ATF. It's made for Allison transmissions mostly, busses and such. I also ran the engine on Amsoil ACD, a straight 30wt from it's second oil change up until I switched to Redline. Other than a brief stint in extremely cold weather where it got Mobil One 0w-20 it's only had two brands of oil in it, in it's whole life.

Around 75-80k I switched the engine and transmission over to Redline. The transmission got Type F, no mixing, just the heavyweight racing oil. The engine also got Redline 5w-30 and other than a brief OCI on 0w-40 and a mix of the two, the engine has always had a 30wt.

So it's had Type F in it from about 75k to the current 124,000 miles. No sign of flare, just good shifts. I also replaced the pressure switches for the 3rd time about a month ago. If I had to pick out one thing I would improve on with the shifting it would be a slightly sloppy 1-2 shift sometimes, nothing bad, nothing most people would notice.

Well, I got bored. I wanted a change and I wanted to keep it in the Redline family if for nothing else than the great base stock. After looking at how thin even the Z1 was in colder temps and how thin the DW-1 is in colder temps I decided to try something thinner. In my climate it really doesn't matter because it rarely gets down to freezing in the winter and my garage rarely gets below 50F in the winter anyway so I'm perfectly fine running thicker than stock fluid.

With that said about stock fluid being much thinner in the cold weather than just about any other fluid, it comes with a price. We know Z1 had a crappy base oil so you don't get a viscosity index (VI) in the 200s without lots of viscosity index improvers (VII). I won't go into detail yet but if you can avoid them or at least reduce them you should. So yes, the stock fluid was thinner in the cold but it could come at a price, likely hard part wear. The fluids I chose still do not have a VI as high as Z1 and DW-1 but they're friction modifier free and they're plenty thin for winter in any part of the US.

So on to my new setup. I wanted a more modern fluid. There's absolutely nothing wrong with the D4 and Racing and LW Racing, nothing at all, I just got bored. I chose to use a Dextron VI which would be Redline D6. It is thinner than D4 by a little. It's nearly twice as thin as the Racing fluid. It offers a more modern additive package but since we're talking aftermarket fluids, there's nothing to say that the other fluids I've been running don't have a similar additive package, FMs excluded in the Type F's case.

I wanted to go all D6 but I just couldn't allow myself to load the transmission with lots of friction modifiers so I used two quarts of D6 and one quart of lightweight racing (Type F). I wanted to hurry up and do this while the weather is still fairly cool. I didn't mind going a little on the thin side since the other half of the fluid in the transmission (I did only a 1X3) is the thicker racing fluid.

If I like the new combo I'm going to buy a bunch more and do a flush with it.

So at the risk of putting my foot in my mouth down the road I decided to do a quick test drive and report back. I've got about 5 miles on it, some through residential neighborhoods and some on surface streets with a speed limit of 55, enough to check out torque converter lockup.

My first impression is it seems to go into gear quicker. It might be placebo, I screwed up by not timing it before I did the switch.

There are two for sure differences. One is the 1-2 shift is less sloppy or maybe a better description is it's quicker. It shifts completely normal just like the other gears do. It was fine before but that was the one thing I would worry about from time to time. The second difference is torque converter lockup. It got quicker when I did the switches a month ago and now it's even quicker. The lockup can't be felt but it definitely locks up in about half the time it used to. I think I'm going to consider this a good thing but it could go either way.

It seemed to have a little less "jerk" as I would be heavy into the throttle and abruptly lift with the resulting upshift. Again, it shifted better than stock with the other fluid but this is getting closer to perfection.

On the downside, the slight whine the transmission has had since the car was new with 8 miles on it seems to be a little louder. When I first put the thicker racing fluid, the whine nearly disappeared. Now it's there. Very faint but there. The other whine when it's in park or neutral is pretty much gone so it solved one problem and created a new one. In the drive through, there was a slight reduction in noise. A reduction that no one in their right mind would even notice but I"m not in my right mind lol.

I'm thinking as I replace the fluid again I'll probably do half D6 and half Type F which is kind of close to what it currently has in it right now anyway.

Anyone who does not like mixing fluids, I think the D6 would do great by itself. IMO it makes D4 nearly obsolete. Or said another way, anyone who is currently using D4 might be better off switching to D6 the next time the fluid is changed, especially if you live in a cold area.

I've got to drive across town to the dealership to pick up a wheel lock set since I drove off with the lock still on the lugnut the other day so that will be a great mix of stop and go and freeway.

Another reason for wanting to go lighter is the design defect we all have. The exhaust on the 3rd gear circuit is too small and can cause the 3rd gear clutch packs to drag on the automatic 4-2 downshift. I figure a thinner fluid should have an easier time allowing it to relieve pressure through that little exhaust port.

And yet another reason for wanting to go thinner is to bring torque converter stall speed up a little, even if it's only 100rpm. I'll need more time with it to determine if that's actually happened. It seems like it's a little looser but it's way too soon to tell for sure.

Oh, one more thing.... With the Type F fluid, the drain magnet always comes out with almost nothing on it. I've been used to seeing this for a long time now so any additional wear caused by the thinner fluid should be evident the next time I change it. Luckily most of the wear metals are ferrous and I can tell by the shifts if it's going to be wearing the clutches anymore.

I'll try not to update this until I have more miles. It's easy to get excited about a new product and write a glowing review no matter what so I need more time with it. I'll try and be more organized and concise when I update, I just had very little time to write this and wanted to hurry up while the first impression was fresh in my mind.

 

Interesting read. Right now I have mostly DW-1 ATF in my transmission. Would I be better of maybe doing the next drain and fill with Type F and then follow with D6 and Type F? We do get cold winters here (well, at least this year, 53 freezes so far) along with 100+ degree summers so I need an ATF(s) that can handle a 100 degree range from our coldest mornings to hottest days.

 

The DW-1 has a huge viscosity index so if it's cold flow you want, there's nothing out there that's going to be better below freezing including redline Lightweight racing. If you only need the fluid to work in freezing to 100 degree weather, D6 will be right there with DW-1 viscosity wise but with the gap widening in DW-1's favor as temps drop. Still though, down to freezing D6 is plenty thin and it should be much more robust for high temps and high loads. It should also give lower clutch wear and better shifts since frictional properties are closer to DexIII. I can say as of now there's almost no difference from cold operation to hot operation. I left the car out over night to get a 55F cold start and shifting is amazingly consistent from cold to hot but unfortunately it's too late to get a real cold start.

I've been trying to get more info on Redline D6, waiting on a reply from Redline. I've seen two contradictory statements on this fluid. One says it's a thinner D4 and one says it's more shear stable and gives more consistent friction performance over a longer change interval.

My honest thought is the big advantages of DexVI are lost on a good synthetic fluid. The syns already have good sheer stability and low oxidation and just about all of the things that make DexVI stand out in the OEM world.

My reasoning for using it over D4 is on the chance it has a slightly different additive pack and focusing on just the 250F to 32F range it's thinner than D4 and a lot of other fluids. It does have a lower viscosity index than D4 so once you get close to freezing the tables begin to turn and D4 is the thinner fluid. For my climate though, I only care about 32-250F.

I know they did not only use a thinner base oil and call it D6. I has a higher flashpoint than D4 despite being thinner and a lower VI which is a good indicator it's a more robust fluid, probably more shear stable. I would guess its a slightly better base stock than D4 and hopefully Dave at Redline will clear it up.

Onto my short review of D6 and lightweight racing, the one thing that is undeniable is the cranking speed of the engine has gone up substantially. I would never have guessed this would have happened as a result of an ATF. The starter sounds like it's on steroids. I always plug the battery in to a battery tender. I stopped doing this and it's still cranking over just as fast. Taking a second look at the old Z1 and the new DW-1 viscosities as the temperatures drop, they remain exceptionally thin in the cold. I don't put a whole lot of weight on factory fluid specs because they're full of compromises and lowest wear is not always at the top of the priority list. The most likely reason for using such a thin fluid when cold is to get that .5mpg increase in cold weather. Still though, I thought I would give it a try and I like the results. What I'm most interested in is when I pull the drain plug in 10,000 miles. If there's an increase in wear I'm going back to the thicker fluid.

Idle seems slightly less labored when cold. Cold shifts are smoother and not much different than hot shifts. I doubt there will be a noticeable difference if it were a 100 degree summer day but then again, it cranks over slightly quicker even after a drive, where the fluid is well over 100F.

The torque converter does feel slightly looser especially when cold which is good.

I don't want anyone to put much weight on this little experiment because I went from a straight thick racing type F which just about no one uses to a thinner than normal setup. Not only did I change viscosity but I changed frictional properties at the same time. A more valid experiment that you could draw conclusions from would be going from all RL Racing to LW Racing. Both have the same frictional properties so the only thing changing would be the viscosity. I changed two things at once which is bad if you want to know what the cause for the change was.

I think it's a reasonable assumption the viscosity decrease is responsible for the improved starting speed and smoother idle. It's probably the primary reason for better cold shifts with some of the credit going to slightly more FMs.

I also have a pretty good trans cooler, so while the summers here are pretty brutal, the fluid may run cooler (and thicker) than others in the same ambient temp range.

For the bad, full throttle up shifts are slightly slower. Very good though, better than stock fluid but I'm still reasonably sure straight Type F will give the lowest possible clutch wear.

I'm considering a larger cooler and a gauge to monitor temps to see if I can get away with an even lighter fluid. The goal would be to have starting viscosity as close to operational viscosity as possible.

So, I have around 50,000 miles on straight Type F with no problems whatsoever. I got bored and decided to make this switch so I'm in no way abandoning the idea that Type F will give the least clutch wear. Other than boredom, the other reason for the swap is my daily drive changed from 210 miles round trip a day to 3 miles round trip a day where none of the fluids get up to full temp. I'm positive I could go with straight lightweight racing fluid with no additional hard part wear for this type of driving but I want to be able to go for a canyon run without having to change fluids.

Once again I'm writing from my phone so not only is this all over the place but I'm sure I'm leaving out a lot of info and I still don't have a whole lot of drive time. Still though, this is probably my favorite combo so far.

 

IHC--do you know what the transmission exit temperatures were on your car with and without the add on cooler?

I added a thermocouple to 2014 MDX to monitor transmission temperatures to make sure that the Acura cooler provided sufficient cooling while towing (stock fluid so far) and will add one or two on 2004 TL. TCs were used so that the lines don't have to be messed with to check temperatures at various locations.

A cooler with by pass (this summer) is needed and I would like to select a Redline transmission fluid that will attempt to work in local temperature range of -20F to 105F (car kept outside). I'm using D4, LW & Racing now and I have noticed that the stock DW1 does have some nice viscosities over a wide range of temperatures, with disadvantages that you noted. I was not main driver when temperatures were very low here but believe the fluid worked fine even when first driving the car in the morning (no external cooler). The larger cooler with D6 makes good sense to consider!

 

I have a 2004 acura mdx i wanted to do my own flush this weekend. I bought the right fluid. do you know what tools are required to do this thank you

 

I'm not sure I want to subscribe to this thread because no oil thread in the history of time has ever gone the way it was intended, but I'm in..

 

Damn IHC.. you've run Z1, ATD, D4?6?, Redline Type F, now this.. Anything else?

 

Sounds like a lot of research funds, I believe there was one other amsoil that was ran.


Will put a good word in for D6 as an FM additive for those of you that may hit too much Type F fluid. Given that your area does not go 0

 

IHC - I'm getting confused with what fluid to use now. I have an 08TL that I bought about 6 months ago and the dealer just did a fluid change. I'm not really intune with my transmission shifts since this is my first auto trans car. I do feel some of the up/down shifts. They are not jerky shifts. When would you recommend when I should do my next fluid change and with what. I'm in Sacramento so my temperature requirements should be the same as yours. I'm also interested in a trans cooler if the car does not have one. How did you setup your cooler? TIA