Clean differential fluid

2003 with 245k miles.
Was going to change the rear differential oil. It was on an incline so when I took the fill plug out, some oil was dripping out, and it was about the same color as the new oil, a light brown. I bought the vehicle at 180k.
Didn’t talk about the differential, So I’m wondering if it’s most likely that the oil was changed fairly recently before I bought it? All the videos I’ve seen of differential oil changes have the old oil coming out black.

The reason I’m asking is because I’m getting some noise from the rear and my mechanic wants to rule out and change the differential oil first.
He hasn’t driven it yet just going by what I’ve told him.

 

Differential oil is cheap, so if the mechanic wants to change it to rule something out, spend the $20 to change it. But to answer your question, old diff fluid is dark and smells like burnt ass.

 

$20??
It would be $45 in oil alone doing it myself. That’s the cheaper oil too.
Mechanic wants $120.
But my fluid is light and smells like unburnt ass, so I’m conflicted.

 

Well take it home and do it for $45?

I'm not understanding the conflict here. Mechanic isn't working for free. $120 doesn't seem excessive.

Maybe whoever you bought it from used the wrong oil? Make sure it got the right stuff then go from there. How long ago did you buy the 4R? Sounds like the PO might of heard this noise as well and already tried the oil change then decided to dump it.

 

I couldn’t remove the drain plug. Sorry forgot to mention that. I’ve had it for 4 years, put 60k miles on it. The noise is only in the past couple months. I brought it back to the shop that did the rear brakes a few months ago after someone told me it sounded like a brake issue. They ruled out the brakes and said it could be the bearings but would need to wait until the noise gets worse. I guess it’s not that bad of a noise.

 

Is it a limited slip, locker, or open differential?

Walmart.com shows Super Tech at less than $6/qt.

ETA: you put 65k miles on it and it runs clean? I'm surprised. I change my differential fluid much more often than that.

 

I'm going to say no f'n way is its clear as day 1 after 60k.

 

I have no idea.
It calls for 75w90. About $10 at Walmart but much better. Thanks for the tip!

 

Since adding my ARB I have used supertech gear oil and changed it at 20 and 40k. It’s very affordable. I’ve also been running supertech 5w30 full synthetic in the engine since new. With the transmission and transfer case I will be a bit more selective.

 

When i changed all my 3 fluids they all looked good, but I had no records of when they were changed. Most recommend 30,000mile intervals so changing it should bring peace of mind and rule out any issues there.
Old fluid probably gets acidic after a while and you may run the change of premature seal failure.

 

I did my rear diff fluid after an unknown previous fluid change interval. Still looked good, still stinks tho, but i had already planned on changing it, so i did anyways.

 

It seemed to me the new stuff stinks pretty bad from the get go as well