is a differential gear oil with limited slip additive, or additive added to straight
gl-5/6 80w-90 needed?, helpful?, harmful?, uneccessary??

a torsen uses gears, is the additive only for "clutch" type LSD's.....

my diff started(?increased)making noise after 5 track day week, and fluid was
thin like water? is that breakdown from heat. the fluid was initially redline with additive, but then changed to unknown with added additive by not me(inadvertently done when other driveline work was actually needed).

service manager at local Honda said best to just use straight 80-90.............. diff noise now much improved.

does OEM honda diff lube have limited slip additive?

 

Limited slip additive is needed for those differentials with clutch packs, not the Torsen design. I don't think it will hurt if you use a lube that has it but it is not needed.

It also seems to me that the 80W90 lubes (M1, etc.) are a little thin so I have taken to using RL heavy ShockProof and changing it a couple times a year.

There does not appear to be a Honda diff lube and I have seen different dealerships use different products.