Thanks, Dana, that helps with what Dennis said last night. I would assume that EP additives in GL-4 are sufficient, then, since that's what VW still calls for. In that regard, it would make sense to me that the extra corrosion of brass synchros caused by GL-5 wouldn't be an acceptable tradeoff for the extra (unnecessary?) EPs in GL-5? I'd still love to hear any updates/opinions on the subject, since I've just rebuilt a syncro tranny and have the option to go GL-5 if it makes sense. Sniff, sniff....her whole life ahead of her....makes a parent proud.... :) tx, bmc :) "Faith will move mountains, but you'd better bring a shovel...."
> > Here's a tidbit on the subject: > > GL4 vs GL5 from pennzoil's site: > > What happens if API GL-5 gear oil is used in an API GL-4 gear oil > application? > > API GL-4 and API GL-5 products typically use the same extreme pressure > (EP) additive system, with the API GL-5 having about twice the > concentration of a API GL-4. In service, these additives become active > under extreme load and temperature when the protective oil film can be > squeezed away. EP additives work by forming wear-resistant compounds with > the metal of the gear tooth surface. As the gears mesh, these compounds > shield the gear teeth from direct metal-to-metal contact that would cause > wear and damage to the gears. If too little of the active additive is > present, proper protection would be compromised. Too much of this additive > could cause excessive chemical corrosion of the gear surface. If an API > GL-5 gear oil is used in a application where API GL-4 gear oil is called > for, chemical corrosion of "yellow metal" components may occur, such as > bronze synchronizers, brass bushings, etc. This may lead to shifting > difficulties or shortened equipment life. > > -Dana- |
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