[VTpiloteer]

2008 EX-L with 162,000 miles. I changed the Rear Differential fluid with genuine Honda VTM-4 when i purchased the vehicle in July 2020 with 135,000 miles. Over the last 2 years it’s done some light towing (1500lb camper) and some moderate New England mountain driving. Drained the fluid today for a change and the old fluid is still bright pink. (See photo.) the old fluid, on the left, is pretty much indistinguishable from the brand new fluid, on the right.
Is it necessary to change the rear differential every 25 to 30k miles? Is differential fluid different from motor oil or ATF in that it doesn’t darken as it ages/breaks down? Changing the rear diff fluid is easy, but I’d rather not waste fluid — for environmental reasons mainly, but also $$ — if it’s not necessary.
Thoughts?

 

[Tacoma'03Pilot]

I'll take a shot.

No, it's not necessary, if you intend the word to mean "essential to being able to drive it over the next few months". I'm sure that there are a lot of older Pilots out there running on factory VTM fluid.

I assume that as a relatively recent buyer, you're hoping for another 50-100k miles. If that's the case, then the real question (at least in my mind) is "what's the upside / downside in deferring recommended maintenance?"

You can save a few bucks by deferring or skipping a refresh. Environmental impact is probably a nothing, assuming you recycle your old fluids responsibly. So upside is cost of a jug of VTM.

Downside is bigger. The clutches in there are probably why the refresh interval is short. Cook one of those and you could buy a few barrels of VTM for the cost of the repair.

I think it comes down to a familiar bottom line for older Pilots: either maintain it as best you can to keep it alive as long as possible, or stop spending non-essential dollars and just drive the wheels off it. Make that choice and you'll know what to do about your VTM fluid, and everything else, too.

 

[cintocrunch]

The color is great but without sending it off to the lab for sampling you don't know how the additive package is holding up that helps the clutches work their magic. Personally, I'm not willing to push service intervals so it makes sense to me to spend the little money and effort now to know your car is in the best condition it can be rather than extending service intervals and hoping everything is good.

 

[RonnieJ]

You really should be doing a drain and fill of the ATF every 25k-30k miles on your Pilot, and should do the VTM as well while at it. That should be every 2-3 years for most people. Super simple to do, and should allow your drivetrain to live a long and healthy life. Don't forget the transfer case, but that really doesn't need to be done as often, maybe every 60k-90k. I wouldn't base your decision to defer replacement based on color. The rear diff fluid will never be as dark as the ATF.

 

[Nail Grease]

Does it pass the smell test? 👃🏻
Does the old VTM-4 fluid still smell like new? Your nose will know. 😂🤣

 

[VTpiloteer]

Does it pass the smell test? 👃🏻
Does the old VTM-4 fluid still smell like new? Your nose will know. 😂🤣

Good call on the smell test. My guess is that the old stuff will smell burnt-like? I still have the old fluid so I can do a smell test.