Why rear diff fluid early, tranny fluid later

Old 08-03-2013, 09:08 PM
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Why rear diff fluid early, tranny fluid later

I'm just curious about this and couldn't seem to find anything searching. It's pretty common to have the Maintenance Minder recommend changing the rear diff fluid around 15k miles, and then every 30k after that I think. What's interesting is that I have 42k miles and still no indication to change the main transmission fluid (and it appears the transfer case oil goes at the same time).

One would think the main transmission gets more wear and tear than the rear differential but obviously that is not the case?
Old 08-03-2013, 09:15 PM
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I think mine came up at 45K. Sooo...
Old 08-03-2013, 09:19 PM
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BTW transfer case was pretty dirty in both cars. If you are changing it yourself, I thinks it's easier to just do them all at once as it's a messy job. The tranny fluid would be fine to skip and just do every other time for 30K intervals.

Transfer case takes less than 1qt GL-5 SAE90 (I use sythetic).
Old 08-03-2013, 09:31 PM
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Thanks! Looks like it will be coming up soon. Somewhat related....stumbled upon an RL forum about the rear diff fluid change and thought I was on a TL forum. The user mentioned not to forget to fill both chambers. My heart dropped, then realized it was an RL forum not TL. I'm pretty sure our rear diff only has one chamber, or else I'm in trouble.
Old 08-04-2013, 06:41 AM
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Originally Posted by Buffa
Thanks! Looks like it will be coming up soon. Somewhat related....stumbled upon an RL forum about the rear diff fluid change and thought I was on a TL forum. The user mentioned not to forget to fill both chambers. My heart dropped, then realized it was an RL forum not TL. I'm pretty sure our rear diff only has one chamber, or else I'm in trouble.
Hopefully just one... as I only drained/filled one when I did mine.
Old 08-04-2013, 10:07 AM
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Originally Posted by CerberusKy
Hopefully just one... as I only drained/filled one when I did mine.
You are fine.... The TL rear diff only has one chamber to drain and fill.....
Old 08-04-2013, 01:24 PM
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Yes, only one drain hole on the bottom. One in the rear-middle of the diff for filling.

All Wheel Drive Fluid (DPSF) x3


Old 08-05-2013, 06:15 AM
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MM, Pull that shirt DOWN!!!!
Old 08-05-2013, 08:13 AM
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Funny, that's what my wife said too.
Old 08-05-2013, 08:57 PM
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This is just a general comment as I am not sure about the specifics with regard to AWD TL. The differential fluid is a small volume and there is no cooling method. It can get quite hot for long periods. Heat is the enemy; it causes oils to eventually turn to sludge (polymerize). If the differential is a posi trac type (power to both sides all the time) it has clutches which need the additives and clean fluid in order to work properly. The auto transmission (transaxle) has a large volume of oil and it is cooled (somewhat) because it travels on a loop through a small cooling chamber in the radiator. The ATF is probably good for 96,000 km of easy driving in a moderate climate.
Old 08-06-2013, 11:51 AM
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Originally Posted by jim_c
... because it travels on a loop through a small cooling chamber in front of the radiator. The ATF is probably good for 96,000 km of easy driving in a moderate climate, unless you drive like marco
Fixed
Old 08-08-2013, 08:47 PM
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I suspect the early change is due to some conservative decision made regarding a potential reliability risk involving impurities that could be introduced within the rear diff during a 15Kmile break-in period, or it's simply a means for Acura to help pad their dealers' service revenue on a car line with reliability that threatens to make total dealer margin (on sales and service) too thin to stay in business. If the latter, I recommend Acura abandon that tactic and instead encourage their dealer franchises to combine with Audi or BMW, and let the margins from those other lines subsidize the cost of the Acura service infrastructure ;-)

I changed my rear diff fluid on my 2010 at the 15K interval myself, and the fluid looked brand new, and felt brand new. However, I did not have it analyzed and realize visual inspection doesn't necessarily yield an accurate assessment. I'm currently around 43K and awaiting the second notice - will be interesting to see the condition of that fluid.
Old 08-14-2013, 07:32 AM
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The Rear diff service can range anywhere between 8-15K. All depends on how you drive.. The main reason for this, is simple.. The SH-AWD system beats the living hell out of the fluid and in the most extreme cases (Very common in older MDX and CR-V) The differential will SHUDDER on mild to sharp turns in either direction. The Shudder can be minor to very harsh. The fluid wears, turns darker and can no longer do it's purpose. This is the main reason why Acura is no longer going to use the SH-AWD system. Besides.. in the Tri-state area the differential "6" Code is on roughly 10-12K.. In other words every other oil change your also due to a tire rotation and a diff service.

I've been a technician for 10 years and worked for Acura as a Certified Technician for 3 years. The system is great, the up keep is best saved for a DIY. Lastly, I always highly suggest transmission fluid to be done anywhere in the range of 20-25K, in most cases even sooner due to another piss poor design carried over and the fluid takes a major shit.
Old 08-14-2013, 10:03 AM
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Originally Posted by draph
... I recommend Acura abandon that tactic and instead encourage their dealer franchises to combine with Audi or BMW, and let the margins from those other lines subsidize the cost of the Acura service infrastructure ;-)
...

Originally Posted by 04WDPSeDaN
...(Very common in older MDX and CR-V) The differential will SHUDDER on mild to sharp turns in either direction. The Shudder can be minor to very harsh... :P
...

...the fluid breaks down as the result of heat generated by the rear diff which is constantly over-driven and debris caused by friction surfaces in the clutch packs.
Old 10-28-2013, 01:16 PM
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Old 10-28-2013, 02:27 PM
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Hey Marco Buddy: The ATF cooling circuit for the fwd car is different than the one for the AWD. It seems (I think) the AWD had the external cooler all along but the 2 WD did not. They changed it so both cars have the external cooler as of 2011 or 2012.
In any event, I change my ATF once a year although a drain and refill only replaces half the fluid. I think this is a good compromise. It will go 100,000 km on the original ATF if the car is driven gently I imagine.
I don't have SH-AWD, but if I did I would change the diff fluid frequently.

Oh yes, nice pic too.
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