nckennyb said

According to the tech editor at Mopar Action, Rick Ehrenberg, if you use GL-5 gear oil the syncros can't bite enough because they were made for GL-4 and older oil.

Click to expand...

In applications specifying API GL-4 quality lubricants, use of API GL-5 lubricants with higher extreme pressure additive activity/concentration can damage these ‘soft’ metal components. It is not intended for use in ‘limited slip’ applications and does not contain friction modifiers which can interfere with proper synchronizer performance.

Click to expand...