Changing my ball joints I lost a lot of diff oil from the axle tube and all I can say is that I wasn't thinking clearly. Exhausted, sunburned, hot... I grabbed the "only" gear oil I saw in the garage thinking that must be the one, laid on the concrete, and pumped it full of 85w140. Later, when I was putting things up, I found a cache of 70w90.

I live in Texas so it is real hot right now. I searched the forums and it seems either will do but most of my driving is highway and I have 150,000 on my truck. No idea whether I mixed oils.

Did I mess up? I cannot recall which oil is in the diffs and transfer case. I have a few cars/trucks so maybe the 85w140 was for something else.

 

Nah, I have 85w140 in mine. It's just heavier than factory and better for more heavy duty uses, but won't cause you any problems.

 

Eases my mind. Thanks, Alex. I'm probably due for a complete drain and fill this winter anyway... would you stick with the 85 or go down to a 70?

 

Stay with the heavier oil be it synthetic or not, the gears will wear less and cooler.

 

The Rover diffs in Series Land Rovers, which are exactly the same design as Discovery diffs, spec'd 90w.
You're fine, I've been running 85w140 for 40 years, from Georgia summers to northern Vermont winters.