There has been a long discussion on the V8 forum about correct grease for transmissions and rear ends that have brass in them. The general opinion is thar GL5 is a no no. What say you?
600W for stock rear end, does not have the compounds that bind to the brass/bronze.
Why bother with that 600 grease. Just go to your auto parts store and get 140.
Just FYI 600W is not a grease- its oil. The original application was as a steam cylinder and worm gear lubricant. Because of its high shear strength properties, it makes a pretty good bevel gear lubricant as well. It is still available from all the major lube oil suppliers- Mobil, Chevron etc. Its just a pain to buy a 5 gallon pail, as that quantity is a life time supply for most folks.
As far a GL5 oil attacking thrust washers, yes GL5 will attack the bronze but in a model T, you would probably never notice the result. Solution- buy GL4 oil if you can find it. GL4/GL5 oil has enough additives to pass as GL5 so be aware of that. Would I loose sleep over using GL5? probably not. Here is a link to a pretty good article explaining gear oil and additives:
I buy it I 600 w from any of the suppliers. Tim
What, exactly is the chemistry with GL5 and bronze parts ? What's in the oil, and what does it "do" to bronze ?
While we're on this subject, was the diff packed with a soft grease at the factory, or filled with oil ? I've read of guys making a "concoction" with STP and wheel-bearing grease to stuff the diff . . . any thoughts ?
It may well have been a soft grease when new, but considering the wear seen on most original parts and the improved seals available now, oil is likely a better option today.
The sulphur additives in GL5 smells bad but helps in a hypoid axle with sliding friction. May tarnish bronze. No sliding friction in a Model T style bevel gear, so no need for GL5.
I Maybe synthetic transmission oil would work?
I use Royal Purple 140. It is compatible with yellow metals even though GL 5. See http://www.royalpurpleconsumer.com/products/max-gear/
Just use this and be done with it. Fuggedabout all that G4/G5 crap, this stuff is made for Model T's and A's anyway.
Thanks Dan for clarifying the meaning of grease! Grease doesn't flow, oil does.
Royal Purple 140 is more than double the cost for 600W from Model T suppliers. $8 for 600W versus $20 for Royal Purple.
Well, if the modern lube increases the life of the rebuilt axle by a few thousand miles, it may well be worth the price difference - parts are still much more expensive than oil.