how much Friction modifier should be used???

[RKRUZEN]

Filling a Buick Grand National 8.5 inch rear axle with 80w-90. a little less than 3 quarts how much friction modifier do I add..it's a posi or locking rear...

 

[bowtie81]

Around here they usually come in a small bottle and i add the whole bottle in.

 

[TURNA]

posi unit add one of the small bottles

lockers add nothing