What i wanna know if there is a big difference in these 2 grade of gear oil:
-75w90
-80w90

Im changing my lube in my Strange 12 bolts and it came with 75w90.But when i came to the store they only got some 80w90.The guy told me that there where probably a small but minimal difference between the 2 and that it would work perfectly.

So can i use 80w90 instead of 75w90?

 

I usually say to run what's recommended but honestly there isn't much of a difference. The question is whether it will bother you every day knowing you put in 80-90 instead of the recommended 75-90 . Seems strange, most places have 75-90 around here, although it may be some synthetic blend...

 

Thats the problem here.They want to sell me the 75w90 but the only got it in synthec formula wich i dont want since its not good for my diff.

 

So can i put 80w90 safely or not

 

You should be fine. If you were changing to something a lot different it would be questionable, but 75-90 to 80-90 is like changing your engine oil from 5-30 to 10-30, either one is usually acceptable.