Gear oil change question

[alms_lefko]

So when I bought the truck with 90k miles I changed the front/rear/transfer case to Mobil 1 synthetic.

It's been 50k miles and I decided to change it again.

The front and transfer case were still very clean. The rear was a 'little' darker but nowhere near what I expected.

Is it normal for it to not be that dirty after 50k miles? Should I extend my change intervals?

Only reason I ask is because I had the dealership change my transmission fluid a few months ago - so I thought to myself - I hope they did the transmission and not the differentials!?....

 

[Morphyne]

That is expected. 100k is probably all you need on gear oil.

 

[alms_lefko]

That is expected. 100k is probably all you need on gear oil.

Thank good to know.

I'll change the gear oil next time I change the transmission fluid.... at 250k

 

[Drunner97]

Depends on how you use your rig. If you're in 4wd regularly I'd expect it to be dirtier. If your mostly a DD and rarely off road, you could go longer. I changed my rear after 20k of DD and off roading 1-2x a month after about 8 months and it was disgustingly dirty. Front wasn't bad when I changed my CV axles. Changing out my transfer case next weekend and it has almost 30k on it so I'm curious to see how it looks.

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[jreask]

Depends on how you use your rig. If you're in 4wd regularly I'd expect it to be dirtier. If your mostly a DD and rarely off road, you could go longer. I changed my rear after 20k of DD and off roading 1-2x a month after about 8 months and it was disgustingly dirty. Front wasn't bad when I changed my CV axles. Changing out my transfer case next weekend and it has almost 30k on it so I'm curious to see how it looks.

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Why would it be dirtier if using 4WD more?
The TC usually looks very fresh when I change it. Front diff usually looks about like the rear diff, maybe a little cleaner.

 

[Drunner97]

Why would it be dirtier if using 4WD more?
The TC usually looks very fresh when I change it. Front diff usually looks about like the rear diff, maybe a little cleaner.

Front and transfer case are only in use during 4wd operation. Rear diff is used daily regardless. The more you're in 4wd, the more the gears and gear oil is being used and heated. Hence breaking down quicker and becoming dirtier with use. Of course a v8 front and rear diffs are used daily and transfer case is only used going into 4lo. There are intervals for a reason. Oil, regardless of engine or gear, will break down and get dirtier with age, heat, and mileage.

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