Posted 2018-05-15 11:39 AM (#563434) Subject: gear oil question
Member
Posts: 26
I am not sure I have ever seen this answered. I have the early style limited slip used from 58 to mid sixties that I will be using. Would it hurt to use synthetic gear oil in that unit or should I use conventional gear oil? What about additives?
Posted 2018-05-15 2:03 PM (#563447 - in reply to #563434) Subject: RE: gear oil question
Extreme Veteran
Posts: 406
Location: Hilltown, PA
To the best of MY knowledge there is no issue with using synthetic in an older limited slip unit. If someone knows otherwise I'd be interested to know as well.
As far as additives it depends on what you want.
Most additives are put in limited slip units to reduce chattering during turns. This seems like a good idea until you think about why the unit is chattering, and why you put the LS in in the first place. Additives reduce chatter by allowing the friction components in the LS unit to slip more easily, preventing chatter when the axles are forced to move at different speeds as when turning.
What many folks don't realize is this also allows those same components to slip more easily when driving straight - kinda defeats the purpose of the LS in my opinion.
I had an 01 F350 with a clutch type LS in it that chattered a little from day one. It ran synthetic w/o additives, and I serviced it according to the factory schedule. After 140K the chatter never got worse, and I never found clutch material in the oil when I drained it. On the other hand that truck was an animal in the snow and could push snow like nobody's business. So for me a little chatter was just a reminder that the diff was working
Posted 2018-05-15 2:06 PM (#563449 - in reply to #563434) Subject: RE: gear oil question
Expert
Posts: 3777
Location: NorCal
I've used synthetic in the clutch-type Sure-Grips for years. Red Line is my preferred brand, it meets all the Chrysler specs for limited-slip differentials.