Rear diff drain interval

supton · Dec 12, 2015

I bought a case of Mobil 1 75W90, to replace the same that I put in the truck a couple of years ago. Only 28kmiles on the oil change. I pulled the fill plug on the rear diff, and the oil looks as clean as when it when in.

I'm thinking... I really don't need to change. 30k on a synthetic fluid, zero towing, mostly highway driving. Not only that--this diff holds 5qt. That's a lot of fluid to wear out.

Thoughts?

expat · Dec 12, 2015

I would say, no.

Seen rear diffs with 100k's +++ running on factory fill.

RamFan · Dec 12, 2015

What does the manual recommend?

If nothing, I'd say every 60-75k miles should be good.

supton · Dec 12, 2015

Originally Posted By: RamFan
What does the manual recommend?

If nothing, I'd say every 60-75k miles should be good.

Duh, not sure why I didn't do that...

Toyota makes it hard to find, but it looks like:
-inspect every 30k. No required replacement interval
-if towing: replace every 30k

Transmission oil is similar:
-inspect every 30k
-if towing: replace every 60k.

Guess I worried over it for nothing. Will do after 50k or 60k methinks.

aquariuscsm · Dec 12, 2015

I usually just do both once a year.

Greasymechtech · Dec 12, 2015

Looks mean little. UOA the fluid for its condition.

A good diff and fluid can last. There is no fixing bad different and bad fluids. Tundra and Mobil 1 have pretty good reputations.

If not working the truck, check cold level yearly and push that synthetic for 60k.

Kestas · Dec 12, 2015

Originally Posted By: aquariuscsm
I usually just do both once a year.

Time means very little. In my case it would mean changing it every 5K.

philipp10 · Dec 12, 2015

how about never. Rear diffs never wear out.

Al · Dec 12, 2015

Originally Posted By: philipp10
how about never. Rear diffs never wear out.

I would have to disagree. I change the rear diff on my subaru every year. Its a cheap shot.

philipp10 · Dec 12, 2015

Originally Posted By: Al
Originally Posted By: philipp10
how about never. Rear diffs never wear out.

I would have to disagree. I change the rear diff on my subaru every year. Its a cheap shot.

Trolling post? I think not. Never changed the rear diff fluid and I have been driving since the late 70's. Rear diffs never went out. At least in the older cars, they were designed so stout there was no point. Guess I cannot say how it is currently.

supton · Dec 13, 2015

Originally Posted By: philipp10

Originally Posted By: Al
Originally Posted By: philipp10
how about never. Rear diffs never wear out.

I would have to disagree. I change the rear diff on my subaru every year. Its a cheap shot.

Trolling post? I think not. Never changed the rear diff fluid and I have been driving since the late 70's. Rear diffs never went out. At least in the older cars, they were designed so stout there was no point. Guess I cannot say how it is currently.

How many miles on each vehicle? I didn't drive in the 70's but my recollection was that 100k was a lot, and 150k was exceptional. I'm already at 100k and aiming for 200k. So I'm not sure that what was applicable in the 70's is applicable today.

Besides, "stout" today just means poorly designed. "Properly designed" today means it'll go about 150k, then we'll get that buyer back in the showroom--anything more is a waste of money in design & metal.

mjoekingz28 · Dec 13, 2015

That is sizeable....mine is about 5.5 pints, so your diff capacity is about double. Are Tundras 250s?

It sounds like 100,000 intervals on regular duty would be ideal with synthetic. But if there is no drain plug, maybe you should just check and add as it seems it was not meant to be exchanged-only topped off.

Now, conventional or special circumstances like that Dodge I have read about on here, sems 30,000 would be appropriate.

What are big rigs running? Half a mil?

supton · Dec 13, 2015

Some like to argue that Tundra's are overbuilt and really are 3/4T class, but on a 1/2T chassis. Something to that effect. I won't wade into it, not on a non-Toyota board!

It won't end pretty!

Does have a regular drain plug, and a fill plug, so it's stupid easy to drain and fill.

Something that is really weird for the Tundras: the bigger 5.7L trucks use a rearend that holds 4qt, but the lesser 4.6L trucks take 5qt. Both are open differentials; the 5.7L uses only a 4.3:1 ratio while the 4.6 could be 3.9:1 or 4.1:1, so I don't think it's due to a larger ring&gear. Odd trivia of the day.

philipp10 · Dec 13, 2015

Originally Posted By: supton
Originally Posted By: philipp10

Originally Posted By: Al
Originally Posted By: philipp10
how about never. Rear diffs never wear out.

I would have to disagree. I change the rear diff on my subaru every year. Its a cheap shot.

Trolling post? I think not. Never changed the rear diff fluid and I have been driving since the late 70's. Rear diffs never went out. At least in the older cars, they were designed so stout there was no point. Guess I cannot say how it is currently.

How many miles on each vehicle? I didn't drive in the 70's but my recollection was that 100k was a lot, and 150k was exceptional. I'm already at 100k and aiming for 200k. So I'm not sure that what was applicable in the 70's is applicable today.

Besides, "stout" today just means poorly designed. "Properly designed" today means it'll go about 150k, then we'll get that buyer back in the showroom--anything more is a waste of money in design & metal.

agree, vehicles back then usually only went to about 150k. I would argue though, that differentials are supposed to be sealed and if they are, I doubt changing the fluid is necessary very often if at all.

FastLane · Dec 13, 2015

I change the Silverado rear diff every three years or if I think I submerged it. I tow my fishing boat all over. The Mobil 1 75W90 comes out looking almost new. I'm sure you could push it a lot longer if you wanted too. 3 years is probably 50,000 kms or 30,000 miles.

zuluplus30 · Dec 13, 2015

Wife's Silverado gets front/rear every 50K and the Jeep gets front/rear every 30K. The Jeep gets offroaded and submerged several time a year, hence the shorter intervals. I generally check for water ingestion a couple times per year. The Silverado's diffs are generally very clean even at 50K. If I wasn't towing frequently, I'd do 100K.

mjoekingz28 · Dec 13, 2015

Hey zuluplus30,

How do you check for water ingress?

Siphon a sample and see if it looks muddy, cloudy, etc?

Or a rise in the level?

zuluplus30 · Dec 13, 2015

Originally Posted By: mjoekingz28
Hey zuluplus30,

How do you check for water ingress?

Siphon a sample and see if it looks muddy, cloudy, etc?

Or a rise in the level?

Syringe with a clear tube and siphon it out. If it's not hazed/cloudy I call it good. I generally only check them if I run a trail that completely submerges the axle. I use lube-locker gaskets instead of RTV and the only time I've ever had a problem was getting too deep in a mud hole and the breather tube went under. Never hurts to check though.

I don't check the Silverado though. It's got a mild lift and my bass boat floats shallow so the rear end never gets submerged.

Al · Dec 13, 2015

Originally Posted By: philipp10

Originally Posted By: Al
Originally Posted By: philipp10
how about never. Rear diffs never wear out.

I would have to disagree. I change the rear diff on my subaru every year. Its a cheap shot.

Trolling post? I think not.

When did I say you were trolling? I said changing was a cheap shot (easy, simple)

hattaresguy · Dec 13, 2015

I'd never change it again, the first two changes were a waste of money.

Differentials never fail from fluid. They fail from water and heat from towing, if you do neither don't worry about it.

On a lot of trucks they simply leak at some point and get changed anyway, like on most GM's...

The oldest/highest mileage rear end I ever did was on a Mercedes with 290k on it. The fluid was 17 years old and perfectly clear as was the inside. Replaced with M1 and if the car is still on the road I'm sure its still in their doing fine.

Rear diff drain interval

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