Originally Posted By: Buick8
Are most brands in the USA yellow-metal friendly now, or is care in selection still required? Question involves replacing the diff lube in a Rolls-Royce Silver Shadow, and a couple other older cars.
For what it's worth.
I rebuilt my Triumph Spitfire 20 years ago, the diff was fine, but I did change the lube, I used GL5.
After about 5 years the diff is getting noisy and there is a lot of slack in the gears. When I reboved and dismantled it, the gear lube was a Green colour and there was NO trace of the planetary gear thrust washers (they are/were yellow metal.
On rebuilding the diff again, I used GL4 and have not had an issue since.