My '08 RL is approaching 110K miles and the transmission fluid's never been changed. I checked the owner's manual and it said to change it when the MID gives the indicator that maintenance is due. However, my local mechanic said it should be changed every 100K miles or so. Should I go ahead and change it or am I good waiting on the car to notify me?

 

CHANGE IT!! And do a change on all the other drive line fluids now!!

Rear differential every 30K, ATF every 60K, and Transfer case every 90K. In your case I would change the ATF, drive another 5K, and change it again. You'll hear about the "3x3" method....I'm not a fan.

There is a maintenance manual available around here, I think in the Garage section? Here's the schedule I use for my '07 RL:

 

So what type of rear differential and transfer case fluid should I get? The owner's manual says to get Honda ATF-Z1 for the automatic transmission fluid so I know that, but the other two?

 

Remember, Search function is your friend out here. Here's a quote from this thread:
Transfer Case Fluid Change? - AcuraZine - Acura Enthusiast Community

"The RL uses DW1 in the transmission, DPSF in the rear differential (2 chambers), and 80w-90 hypoid gear oil in the transfer case. These are all listed in the very back of the owners manual with the exception that ATF-Z1 is discontinued and the replacements are as I just explained."

Do some looking around via Search and get yourself smart. Lotta good stuff out here. Good luck.

 

Hey so you're telling me to change the rear differential but what about the front differential? Also for the transfer case, SAE 90 would work just as well as 80W-90 yeah? And I called the transmission shop about the service and they recommended not changing it unless the gauge cluster display says to do so. You sure I need it changed?

 

I'm not sure what you're calling the "front differential". If you mean the automatic transmission, we've all addressed that.

Please carefully reread my first post, and then follow carefully the advice from me and others on this thread.

That's the best answer I can possibly give..

 

He's right about the existence of a "front differential" with fluid separate from ATF. I didn't know about it either until I learned about it on this board. The proper name for it is the "front transfer case," I believe. Pretty sure it gets much, much thicker fluid than ATF, more like rear transfer case fluid. But this can be looked up, of course.

 

So you'd recommend SAE 80W-90 over SAE 90 oil for the transfer case, or does it not matter?

 

Personally, speaking as a non-expert, I'd choose 80W-90 but it doesn't matter much. The meaning of these numbers is that 80W-90 (W for Winter) is that 80W-90 should behave just like SAE 90 in warm temperatures, and the "80W" part just means it'll thicken in the cold a little less. So in theory, 80W-90 has an advantage in the winter and no penalty in the summer, just like 10W-30 motor oil compared to straight 30 weight.

But that said, new 90 is probably better than 80W-90 with 150,000 miles on it. And to be blunt, when you're talking about 15-year-old cars with low book value and famously durable transaxles, the stakes are pretty low.

 

Here's that answer, complete with me looking stupid:
https://acurazine.com/forums/second-...change-955174/

 

The front differential is in the transmission housing and is thus lubricated by ATF.

The transfer case has a hypoid drive and therefore requires an extreme pressure (EP) oil with added sulfur. Or sulphur. That slows down the shredding of the oil molecules by the hypoid gears.

The W merely stands for 'weight'.

The rear diff requires a strange hybrid oil, since it has most of the components of an auto tranny plus a hypoid drive in it.

 

With all due respect, sir, you are disastrously wrong and anyone who follows your advice will promptly destroy their front differential. The linked video is not from an expert, but it provides clear visual evidence that the front transfer case — or if you prefer, the front differential — does in fact have its own separate fluid fill and drain holes, each sealed by a bolt. It requires much thicker fluid than Automatic Transmission Fluid (ATF), and you'll notice this owner is using same (75W-90, in his instance).

In addition, the "W" in lubricant weights does in fact stand for "Winter." It's to tell you that in cold temperatures, the lubricant behaves like a lighter-viscosity (thinner) lube — in other words, that it has additives to make sure that cold temperatures don't thicken it as much.

I apologize if this reply does not sound courteous, but your misinformation is positively dangerous to ou8r fellow readers' cars and wallets. Please make sure you're more fully informed before you make such confident statements and argue so aggressively with others.

 

What he said^^^^^^!! Just maybe you should think about having this all done at a qualified mechanic's place. I think you're out of your depth, and not currently getting sound advice from everyone.

I'm out!!

 

Stands for 'weight' over here - you are right about the SAE definition.

Unfortunately you are conflating the front differential gear (found on the front driveshafts, part of the tranny) with the transfer case which is separate and is a simple hypoid (or merely a simple spiral bevel - hard to tell) with no differential in it. It has an oil seal between it and the differential housing, from which it takes its drive.





I'm sorry you found my reply aggressive instead of factual, but that might be projection.

 

I appreciate your passion for the RL, and I defer to you on what's the correct name for the front transfer case—as I said before, I don't claim to be any expert on that. To me, the important part is the impression we leave on others who read this and depend on it for working advice.

The key point is that the transfer case absolutely must not be filled with automatic transmission fluid. If you car is still running—and I trust that it is—we both agree on that, and that's all that matters to me.

 

That is indeed what my post implied.

For clarity, although differential gearing does involve four bevel gears, the torque and speed differentials between half-shafts is quite small and the crown wheel is simply helical on a transverse layout. So one is fine with what is appropriate: MTF/ATF/or even engine oil in the case of a Mini or small Peugeot. Torsen or other LSDs might have special requirements.

A 90-degree bend in the drive axis (as in the transfer case) is transmitting a lot of torque - up to 70% in this case, or 100% on an inline FWD/RWD layout. That's a lot of shear with a spiral bevel drive, which is why an EP oil is specified.

That is why the Transfer Case oil should be changed frequently and not overlooked. There's been a few knackered like that over the years...

 

Thanks for sharing. That's a lot of useful knowledge on why a heavier oil is required.

 

Are you missing the second book in the owners manual set, the maintenance and service guide ? The precise service items and mileage/age for each is listed in great detail - it tells you exactly when you should change each fluid etc.
If you haven't been following this, you've probably missed a whole bunch of other things too

Here's what the 5 year age page looks like :