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Use the GL-4 with LSD additive. I've used Valvoline most often.


Russ, I think you meant to type "use the Gl5" for the rear diff.

The hypoid rear gears need the EP level that's in a GL5.

GL4 and Gl5 both have sulfur / phosphorus as an EP additive, but Gl5 has more. For the LSD unit, as Russ pointed out you will get chatter without it as well as more metal from the clutches.

I have had good results using Redline GL5 with the LSD additive premixed.

87 Turbo Intercooled Raider, roller cam, torsen rear diff, LSD front diff, lockup auto with modified converter, V6 brakes, low transfer case gears...