Sure grip fluid?

[Fern]

Can you sure synthetic oil in a sure grip rearend?

[headejm]

I run synthetic gear oil and one bottle of Ford friction modifier in my 1970 sure grip. No problems at all.   

[bc3j]

I use 80/90 weight GL-5 rated with no additives with no problems. I followed the service bulletins issued for the recommended fluid for the Sure-Grip.

[dodj]

 I used amzoil synthetic severe gear.  85/90. No additive required with severe gear.