final drive and transmission oil modern

My opinion is to use the current spec 70-90 weight oil of your choice. I use one gear lube, an 85-140 multi weight, in everything here except some newer limited slip differentials. I have used 50 wt in the transmission of our D69U. That was mainly because of the volume required ($$$$) and the fact that i had a barrel of Chevron Delo 100 50 weight I had no other use for. Seemed to work out fine in both engine and transmission 😊

I think the modern gear lubes are back compatable with older spec fluids.

You can make the study and discussion of oil a hobby in itself. look at a recent post by me on this topic, there is a good link to a guy smarter than me about relevant oil issues in older motors.

Just FYI, from Walmart .com I recently ordered enough 85-90 gear oil and Mobil delvac 15-40 SHIPPED ( to change all fluids in my D6) to me for way less than any others price. If I recall the 15-40 was about $12.00 shipped per gallon.

My conclusion after a few days of reading was modern oils are fine, when using the correct type.

I use the GL-1 in my finals and transmission, don't want the GL-5 attacking the brass.

You can make the study and discussion of oil a hobby in itself. look at a recent post by me on this topic, there is a good link to a guy smarter than me about relevant oil issues in older motors.

Just FYI, from Walmart .com I recently ordered enough 85-90 gear oil and Mobil delvac 15-40 SHIPPED ( to change all fluids in my D6) to me for way less than any others price. If I recall the 15-40 was about $12.00 shipped per gallon.

My conclusion after a few days of reading was modern oils are fine, when using the correct type.

[quote="TOGNOT"]You can make the study and discussion of oil a hobby in itself. look at a recent post by me on this topic, there is a good link to a guy smarter than me about relevant oil issues in older motors.

Just FYI, from Walmart .com I recently ordered enough 85-90 gear oil and Mobil delvac 15-40 SHIPPED ( to change all fluids in my D6) to me for way less than any others price. If I recall the 15-40 was about $12.00 shipped per gallon.

My conclusion after a few days of reading was modern oils are fine, when using the correct type.[/quote]

would you please link to this discussion? i can't find it

Click on my screen name :Tognot . You can then go to " my posts" on 5-13-17 I posted the link. I tried to copy and put here but no luck.

Thanks. i found it. it is funny because the Cat 50 w transmission oil has a higher viscosity at temp than the 90 weight gear oil. but according to the article viscosity is bad. i found this in another forum>>Interesting The forestry corp run a few 65's & 85's they had final drive problems at low hours so they ran one with 30 in one side 90 in the other. The 30 side failed early as usual the 90 side was good did the same again, same problem so 90 in the winter 140 in summer months and those machines did big hours with no final drive issues again

Nope! :nono:
A young Collector down in Illinois spent the better part of a winter searching answers on backwards compatibility of gear oil. He went so far as to call the manufacturers to talk to the chemists. What he found is they are not! He now has Chevron mix him up some GL1 oil for his transmissions and other stuff.
Price?
Honestly its comparable to store bought for price. He calls them and orders, they mix it when they have time and ship it to his closest distributor.
BTW 👍
I found out that Tractor Supply carries a "GL1" Mineral Oil for the old Ford tractors that is rated as 90W.

For the oil experts....