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With all the complaints about the A/T on the 2nd Gen RDX, what is it about the fluid that wears out that it needs changing every two engine oil changes as one member put it.
It isn't subject to what engine oil is subjected to (high heat and blow-by, etc).
What hot does the A/T fluid temperature reach? Has anyone taken any readings?
Honda automatics have required frequent fluid changes since forever. Yes heat breaks down the friction modifiers. Check any Honda forum dealing with
vehicles that use this engine/trans combo and you will see that it is not odd. It is only odd to folks new to Honda. Why Honda automatics are different than everybody elses is an interesting story.
I can link to an article about that, but it all had to do with a little Japanese motorcycle company asking Borg Warner for patents and being turned down flat.
Here is a post from the Odyclub about temps in the original vehicle that had this setup:
Remember, that every second oil change fluid change interval I might suggest is a "normal drain & fill" that replaces approx. 1/3 of the fluid.
It also assumes one would use the MID oil % meter and change when it got down to below 15%. For most folks that is like every 16,000 to 20,000 miles.
Back in the late 70s & 80s I had several Honda sticks that had a 50k fluid change interval.
I think the RDX probably puts the least strain on the trans of any of them. It's a real good idea to make sure the trans has all of the available software updates.
And Muzzle the VCM for smoothest operation.
With all the complaints about the A/T on the 2nd Gen RDX, what is it about the fluid that wears out that it needs changing every two engine oil changes as one member put it.
It isn't subject to what engine oil is subjected to (high heat and blow-by, etc).
What hot does the A/T fluid temperature reach? Has anyone taken any readings?
Interesting question:
Have a 2008 Rdx @270k km, here is what i found:
Was under the impression the 2nd gen had more stable transmissions than the first gen (even with a manufacturer stated service cycle at half the recommended one for my version).
Using possibly imperfect methods, saw/estimated ATF temperature spiking at a rate of say 3F/minute during IDLING. 10 minute idling is all it took to get from 200F to 230F with no significant drops.
Stop/go traffic does not allow enough cooling to bring it down. The increase in temp was while the radiator fans kicked in and brought down the coolant temp from a maximum of 212 in my case.
The transmission fluid does circulate through the external cooler then the radiator warmer portion.
So the only explanation that matches observations is that the FLOW of oil is VERY significantly dependent on rpm, with temperature spiking quickly below 2000 rpm, insufficient to keep it below coolant temperature.
I verified it by revving up and it did show a drop in temperature, but not very quickly and not very large. The only way to bring it down quickly i.e within a minute, was driving at above 50km/h.
Cruising on the highway, in the night, I have seen it stable around 170F (maybe canadian winter perhaps had something to do with that ).
I retested after bypassing the warmer portion of the radiator:
The coolant seemed to increase its temperature SLOWER, and transmission FASTER, ONCE IDLING (expect the reverse at driving speeds), with maybe a very minor 10F transfer/flip between coolant and transmission levels. I kept it bypassed and am avoiding stop/go when possible.
*** If you have daily stop/go situations in excess of 5-10' do not recommend bypassing the warmer from the radiator.
Please consider that specific spot temperatures at clutch surfaces can and should be spiking higher than the bulk temperatures noted above. In stop/go situations that occurs maybe 50-100 times per km, while driving and locked in cruise control never.
So what can one do about it?
First do not idle, turn off if faced with more than minute stops.
RHETORICAL QUESTION: HOW MANY TIMES WOULD YOU TURN BOTH AC ON & FULL HEAT ON DURING SLOW&LONG DAILY COMMUTES?
Estimate the maximum stop/go time in minutes from daily commute. Multiply by 3. Add 200F and look up the value in the oil replacement distance by temperature for suggested interval, attached. (there are other similar schedules that also indicate various changes associated with specific increasing maximum reached temperature levels, very interesting reading before one should consider skipping fluid replacement all the way to 100k miles).
Based on the observed pattern, a daily v short 10' stop/go commute would suggest an ATF change about 12k miles, pretty darn close to one every second oil change, about once per year for average annual mileage, and in line with user reported experiences.
Had increasingly harsh gear changes around 60km/h despite more frequent fluid changes. So I felt there was no other way to save my transmission other than explore/try a different transmission fluid, inspiration and possible explanation thanks to dcmodels:
According to product data sheet, REDLINE D6 has it a bit lower at ~6.3cSt, (and a much higher flash point of 480F). https://www.redlineoil.com/d6-atf
While I do not expect the transmission oil temperature to come close to its flashing point, i do consider it linearly indicative of its resistance to temperature degradation in real life. So as imperfect as it is, a 140F difference advantage over Honda-DW1, if true, would imply at the very least a cushion of about 35 minutes MORE commuting time, all other things being equal, ie. with the same change interval of 12.5k miles could be IDLING from 10 minutes to 55 minutes... with smooth shifts unlike other reports for Redline D4 as harsh or notchy, and no need/messy to combine low friction high viscosity oil with low viscosity grades...
So I am been using the REDLINE D6 since last year, around 50U$/gal. online.
Being in Canada the cold viscosity is higher when around 0C, twice in fact, so I have an audible notice to take it easy for the first few minutes (an audible faint growl if I rev beyond 1500 rpm when cold).
There are reports that Valvoline MAXLIFE ATF might also be a viable alternative. Its viscosity is even lower 5.9@100C, flash point @395F, cant find info about 0C, maybe about cheaper than redline (same price here at walmart for 3x the quantity).
Specific to your rdx, thanks to jjrphs sharing his experiences:
*** DISCLAIMER: Due to changing and likely different driving patterns do not consider my experience typical, what fluid you use in your car is your business and your responsibility.
Cruising on the highway, in the night, I have seen it stable around 170F (maybe canadian winter perhaps had something to do with that ).
Hth
Thanks for the responses so far.
My 2017 RDX still has the factory Honda DW-1 fill in it, if that is what the "factory" fill is.
On the highway at a steady 100 KPH (62 MPH) on a 20 minute drive and also where the ATF temperature stabilized for some time, I am not even getting close to getting as high as your temperature.
My LAUNCH diagnostic tester was recording: ATF Temperature, ATF Temperature Sensor Voltage and Speed. Next time I will also have it record coolant temperature although it was exactly where it always is on the instrument panel. OAT was 15C. Terrain is level and I was not pulling a trailer. BTW, speedometer is within 1 count verified with my GPS with cruise on and a level and straight course.
I performed an ATF change on my friend's Hyundai with 95K kms using MAXLIFE ATF since it carried the Hyundai SP spec. Ran it through twice with some driving in between each change.
Sounds good, agreed hwy cruise is best, thats why I posted it.
You are better equipped than I am.
Check both ATF and coolant temperatures while IDLING, after at least 30' city drive to have enough time to warm up. Check trends over a period of at least half of your daily commute.
If you dont find ATF temp spiking well above 176F, then fluid should remain stable and not break down prematurely, so it is easy to follow manufacturer requirements.
During warranty period, changing the fluid type may not be such a good idea anyway, even if the fluid was changed on time.
Should you start to feel gear change glitches and often, despite low and stable ATF temperature levels, look for something other than fluid, fluid screens or serviceable filter, pressure sensors, even mounts perhaps. Let dealer know in any such case to investigate.
As I said, I had a very good reason to switch brands in the first place and did not have to worry about warranty status, you may not have the same pressing need or choice.
Then again if you have a LAUNCH TESTER, may be you do.
Check both ATF and coolant temperatures while IDLING, after at least 30' city drive to have enough time to warm up. Check trends over a period of at least half of your daily commute.
Then again if you have a LAUNCH TESTER, may be you do.
I plan to take a slew of data readings both in stop 'n go city driving as well as on the highway again. Then I'll post the data.
Just curious since I have absolutely no issues with my automatic transmission that so many talk about. It shifts ultra smooth and I am still running on Honda/Acura's VCM. One day I'll hook up the S-VCM that I bought a year ago...got a power pig-tail already hooked up to the + of the battery for easy connection. I'll also post changes in fuel consumption since I keep an accurate record on MS Excel.
Tools and test equipment, one can never have enough. Just look at the hourly shop rate and think of the tools you can buy. I bought almost all of my Snap-On tools in my late teens and still have them. It'll be an absolute-zero cold day in hell before anyone touches my vehicles (I've worked in shops). Same goes for anything around the house: HVAC, electrical, plumbing, carpentry, etc. and it is done "right".
I am sure SNG would have increased further. Would have to verify it though.
Also sure highway use would see it level off around the 125F range (verified the other day).
Will have to repeat when it warms up.
Looks like the thing to do , would be switch to the Valvoline (which I have already done ) and add a cooler for the trans , up front of the rad. I'm going to make that addition.
Looks like the thing to do , would be switch to the Valvoline (which I have already done) and add a cooler for the trans, up front of the rad. I'm going to make that addition.
Well I have never owned a car with an automagic transmission till the RDX, so I have no idea what normal ATF temperatures would be under the same driving conditions.
The cooler, if you need one, will do far more than a fluid brand switch as far as temperatures go, I am sure. Never thought about it much and I haven't looked at the A/T to see what lines are available to connect to, other than the rubber line to the ATF filter.
...
On the highway at a steady 100 KPH (62 MPH) on a 20 minute drive and also where the ATF temperature stabilized for some time...
Originally Posted by Poolman
Looks like the thing to do ...add a cooler for the trans , up front of the rad. I'm going to make that addition.
Originally Posted by Tech
... I haven't looked at the A/T to see what lines are available to connect to, other than the rubber line to the ATF filter.
You found AT temp max out @171F with OAT@66F, much less and stable @125F while cruising. Would be nice to know if the sensor you monitored is located off the oil tub or cold return from external cooler...
By itself this suggests you should not have to worry about premature (<100k miles) temp breakdown of AT fluid, for YOUR DRIVING / LOCATION / CAR. Recheck @IDLE and/or above 90F in to be sure.
For reference: 2017 2wd already has an external cooler and seems to also flow through the bottom of radiator, according to the diagram:
If anyone does heavy duty towing, on hills, hot environment with this car, regularly, then best consider upgrading the cooler to a larger one with its own shrouded fan.
Consider changing radiator coolant more often than recommended to lower the chance of catastrophic failures, as reported in the 1st gen, due in part to the daisy chaining of the coolers. I was lucky to change it at 9 years, before failure... corrosion was already present...
My son installed a tow package into his 2008 Pilot. The package included a trans cooler that mounted up front of the rad. There are units for the second gen RDX as well that bolt in and requiring the removal of the front clip. do do the install. For my RDX, I don't think there is a cooler tied into the rad, I believe there is a small cooler back behind the engine and it's a poor design, it should have been up front to catch more air. Will be looking into this on my next fluid change . Below is a vid on the install for 2015 MDX,,doubt that there would be much different for the RDX
Well wouldn't you know it, I had a look this morning and my 2017 RDX has a cooler just like the one in the above video. Same location: driver's side at the bottom.
Follow the tubes (caution: could be quite warm after drive), see if either eventually hooks into the radiator.
Expect to have one nipple towards the engine&AT and second probably towards this external cooler, or even even if indirectly through the expansion reservoir.
... bypassed mine on the new replacement radiator, not for everyone - I manage to avoid the SNG traffic- .
Follow the tubes (caution: could be quite warm after drive), see if either eventually hooks into the radiator.
Expect to have one nipple towards the engine&AT and second probably towards this external cooler, or even even if indirectly through the expansion reservoir.
... bypassed mine on the new replacement radiator, not for everyone - I manage to avoid the SNG traffic- .
Cheers
Will do when I change the engine oil and oil filter later this month before applying Krown to the car...hate that stuff dripping down on me, so I do the oil change first.
Thank you for the reminder, will have to plan a more extensive refresh on mine, saw some bubbling on the side, the growing areas undercarriage despite an oil treatment in 2018...
Thank you for the reminder, will have to plan a more extensive refresh on mine, saw some bubbling on the side, the growing areas undercarriage despite an oil treatment in 2018...
Cheers
Off topic, but I have been using Krown T32 and then T40 since 1990. That car was rust-free when we sold it at 16 years. I also applied Krown to my 1999 Honda CR-V and it was rust-free after 14 years and is now in the hands of a friend making it 20 years old this month. I have applied it myself since 1999. I never drill holes, instead I pull out rubber plugs, spray and reinsert the plug. Most cars have plenty of them. We tested rust proofing products at work.
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