Mix 80w90 with 75w90 rear diff?

[Luke77]

I have to fill my rear diff of my 60-series, but I do not have enough 80w90.
Can I mix it with manual transmission oil 75w90?

Second question: can I also run it on 75w90 only?

 

[GLTHFJ60]

Does the manual transmission oil have any weird additives in it, or is it just 75w90 gear oil?

You are fine to mix the two I'd think.

 

[Luke77]

Does the manual transmission oil have any weird additives in it, or is it just 75w90 gear oil?

You are fine to mix the two I'd think.

No weird additives, just basic Castrol 75w90.

 

[banieldowen]

should be fine.

 

[rrv333]

I've been running Royal Purple 75w90 for a couple of years now with no problems. I had Marlin Crawler regear my diff's last year and I asked specifically about the condition of my gears and they said they were fine.