<VV> Some interesting facts on Gear Lube
BobHelt at aol.com
BobHelt at aol.com
Tue Apr 7 11:42:25 EDT 2015
I know that this subject is getting quite boring for some of us, but I have
discovered some facts not presented here before and feel the need to
summarize the Gear lube uses in Corvair automobiles.
So here goes~!!!!!
GL-4, GL-5 and MT-1 are the only active Gear lube designations.
MT-1 is for non synchro transmissions so it is NOT for Corvairs
Despite some other differences between GL-4 and GL-5, the important
difference for Corvair 4-spd trannys is the greater slipperyness of GL-5 that
tends to add wear to the synchros if used in our transmissions. Tarnishing of
the brass rings is a non issue since both have protection. Both can be used
in our differentials.
Despite the fact that GL-4 is currently being marketed, the GL-4
designation was inactivated in 2010 according to internet sources, since the test
procedures and equipment are obsolete.
Because of these obsolete equip and procedures for verifying GL-4 by
testing, the industry has agreed to produce GL-4 lube, not the old way but by a
new way. GL-4 is currently being manufactured by adding a quantity of
one-half of the GL-5 additives to the base oil. So GL-4 now is similar to
previous GL-4 oil but not identical.
I was unable to determine exactly just when the GL-X way of rating gear
oils went into effect, but it must have been around 1975, long after the
Corvair ceased production.
Thus, the Corvair requirement of gear oil meeting Mil-L-2105B later
turned into GL-4 (in about 1975). Corvairs NEVER required the GL-5 equivalent
so Redline is definitely wrong about this. And thus I question Red Line's
knowledge of GL-5 applications.
Red Line says their gear oil meets GL-4 but then goes on to say that it is
not for hypoid gears. This a conflict in fact and cannot be true since GL-4
allows use with hypoid gears. Either it meets GL-4 and can be used in
hypoids or it doesn't meet GL-4 for hypoid use.
Another case of Red Line's questionable information.
Bob Helt
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