Driveline fluids at 30K

Just had my mechanic do plugs and driveline in honor of my truck's first 30K. I know I could do it myself, but, I didn't. My mechanic is an old friend and he hasn't seen much of my business since I got such a reliable vehicle a couple years ago.

So here's the thing: he told me the transfer case oil was like new. Rear diff was what he would expect from 30K. Front Diff was almost black. What do yinz think about that? Typical? I'm wondering if I should up the service interval for my front diff.

Has anybody seen variation between front and rear diff oil wear?

 

I think the darkness in the gear lube on the first change is from the assembly lube and gear teeth paint from setting up the differential. I changed the differential fluids on my truck around 7K miles and it was dark. At 30K miles I changed them again and it still looked new. I'm probably going to wait until 100K miles for the next service.

 

I changed the oil in my front diff yesterday at 27k and it was black and the drain plug had 1/8th of an inch of metal muck on it. All other gearboxes are clean, must just be the nature of the beast???

 

This mirrors my experience, and I think it's pretty standard/normal.

 

I changed mine at 30k as well. Front differential and transfer case was like new. Rear was a littler dark. I hardly use 4wd though.

 

I changed mine at 80k to Mobile1 Synthetic, an older guy I work with asked why I wasted my money, his Tacoma has over 250k on it and he's only ever changed the engine oil. He said there's no heat and there for no breakdown of the oil, he also noted he's never replaced a reared or diff.

 

Just did all my fluids last night (F/R diff, TCase, and MT). Rear diff was fairly dark, Tcase was light brown almost looking new, and Front diff was nearly black. Manual trans wasn't terrible, mostly brownish. The smell is what gets ya! I replaced all my fluids with Amsoil Severe Gear

$30 75w-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75w-90, FWIW

 

Has he ever measured the temperature in his differentials? Temps, especially in the rear, can easily exceed engine oil temps. Dino oils run hotter than synthetics. The little 8" ring & pinion in the Tacoma really gets worked hard by the 4.0L. Aside from all that, the long chain molecules in oil that make them slippery and provide the oil film thickness needed to protect the gears, breaks down due to shearing forces, not just heat. Shearing forces in a gear box can be enormous.

Lots of people consider their gear boxes to be sealed units. Some go many miles. Some die early. Fresh oil is cheap, easy insurance.

 

In mine with about 26,000 miles (I bought it used with about 25,500 on it) the front diff was the nastiest looking, Transfer case looked nearly new and the rear diff gear oil had some wear to it.

 

LOL.... obviously the guy has never seen a truck in the rain where the center pumpkin is dry due to evaporating all the water off.

I changed my rear diff at 5k miles... the break in oil was N A S T Y. Front diff got about a half change of fluid when i did my front diff bushing at 9k miles it was OK looking. Trans, tcase, front and rear diff will all get changed at 60k miles, so sometime at the end of this coming up summer.

 

That is the kind of person I avoid when buying a used vehicle.

My oil changes were what most here said, break in oil black and replacement oil looking like new.

 

Since 1991 I have bought 5 new vehicles and 3 used ones. Every damn time I buy used I regret it.

If you're looking at a used vehicle and it's obvious that the tires haven't ever been rotated, run do not walk away. That's a clear sign the vehicle was only ever serviced when the oil light came on. Buy one from the guy (or woman) who has every service receipt ever and the window sticker. Or just go get a new one.

 

I change diffs at 30k. Noticed that front was darker than rear. I change tcase at 50k and fluid looked new. Unless you are running a hell of a lot of mile in 4wd I see no need to change it.