Maybe somebody can help me out on this. I want to change the tranny oil in 2 of my RR 13spds. I have a 5gal. pail (new) of Castrol (p/n 30277) 90w straight mineral gear lube that I was told is the correct fluid for the trans. And I bought several years ago. However, Castrol doesn't make that anymore. I called their tech line and was told the replacement fluid is Castrol (p/n 40927) paradene 220 gear oil and not to mix it with the old part number fluid. I'm worried that I may need more than 5 gal. to fill 1 trans. so what would be compatable? How does one know if what's being drained out of these trannys is indeed mineral gear lube and not say 80-90w? Or, should I just bite the bullet and buy todays synthetic RR oil? Anybody out there have experience with this issue? .....Thanks, Dane

Dane,
My fleet of Freightliners that work back in Green Island use regular gear oil, not synthetic. I change the oil every five years in the transmissions and rear ends and have done this all my life and have never had a failure. I use Kendall products as we take an oil sample with every change. Recently Kendall called and said we had a serious problem with diesel fuel in the motor oil in one of the Cats. We discovered a cracked injector cup and replaced the head. So far I have avoided four catastrophic loses due to oil sampling, and all on regular motor oil.

Dane-----Straight mineral gear oil is somewhat similar ,but won't have the sulphur smell that rear axle gear oil has . And the 90 wt.gear oil is a similar viscosity to 50 wt. engine oil . Your sales rep sounds greedy to tell you his current oil is not backward compatable with what you already have . I happened to have several cases of Pennzoil 50 wt racing engine oil for my last change in my Spicer .

Dane - 90W straight mineral oil is readily available thru your local NAPA store in convenient 2 gallon jugs. Let me know if you need anything.

Thanks for the reply gentlemen. Stan, I will check out NAPA. I haven't been to one in years. I'll likely go that route.

A good farmer friend of mine was at the local TSC store. They have (GL-1) 90w mineral oil 2 gal. jugs on the shelf. So I went and got it there (Brockport, NY store). Only bad thing is the jug says its for 39-52 ford tractor tranny's. I don't care for fords, im a GM kinda guy.

Take the label off the jug!

It's a screen printed plastic jug.! I'm going to dump it in a 5gal pail.