Transmission lubricant for my 1940 LaSalle (GL1 ?)

[Bill Bickle 15098]

Had a conversation with someone re. transmission lubricants  and it was suggested that modern 90 weight lubricants are harmful to the old transmissions;that I should be using GL1 lubricant.  Looking for opinions.

[TJ Hopland]

The little I have read it was some change in GL5 which came out in the 70's that maybe causes problems.  Napa carries a brand called Sta Lube that is a GL4, not a GL4/5 like is most common now days. 

[HerbP]

I found some interesting data on another forum that may be of use:
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2554764

Following with interest...

[TJ Hopland]

Here is a document from the API saying what the differences are/were.     It notes that GL4 and GL5 are the only ones still currently tested and certified by the API, the rest are no longer tested so someone could say they are selling a GL1 but no one is actually checking to make sure its meeting the spec.    The GL6 spec was for the first couple years of the FWD Eldo and Toro.   Its no longer tested because the test rig wore out and low demand since it was only those models a couple years.

http://www.api.org/~/media/files/certification/engine-oil-diesel/publications/1560-eighth-edition-april-2013.pdf   

[Mike Wenrich #1666]

Seems there was a previous discussion on this issue and I recall that old transmissions with brass components should use GL1, if they can find it.  I found it at a NAPA dealer.  They had to order a case of four to get me the gallon I needed, but others were wanting it so no problem with that.  Not normally stocked but available.  This was about one year ago. 

[TJ Hopland]

I just checked my local napa online and they do indeed list a GL1 oil.   Part number NHF 65201  and its showing in stock at my local store for about $13 for a gallon.

And to add a few more bits without really answering the question.....

There are 2 possible issues.   

First issue is 'yellow' metals.  GL5 apparently has some additive that long term isn't good for brass bronze types of metals that were often used in things like transmissions.  Its apparently a thing like lead, zinc, and ethanol.   There isn't a simple easy to prove for everyone test good or bad.   How things are effected seems to depend on how they are used.  Sitting seems to be worse than regular use.   Apparently has to do with moisture and acids forming and its the acids that cause issues with the yellow metals not the additive itself.   Fairly regular use apparently keeps the moisture down so acid levels down so no or minimal issues.

Second issue is a problem for synchronized transmissions.   This is also an area where 'yellow' metals were used so it could be a double issue for those.    Synchros are a delicate balance of grip and slip so how slippery or grippy the lubricant is can really effect how well they work.  Some say that modern synthetic oils are too slippery so they don't work correctly, others say they have never worked better after switching so who knows.

[jmscan06]

I use "Sta-Lube"  API/GL-4.   Found it at NAPA.   


John
#28099
1940 Lasalle 5227c

[Bill Ingler #7799]

Several years ago I switched to Royal Purple which is a synthetic but is non corrosive. A little more expensive but since it is non corrosive, to me that is worth the extra bucks.  Bill