What is everyone using in place of the old castol hypoy LS? Do the SII and SIII XJ12 use the same fluid? Thanks.

 

I use whatever 80/90 gear oil is on sale that day, GL4 or GL5. Valvoline, Shell, whatever. Nothing exotic required

Add some limited slip additive if the gear oil you buy doesn't specify "For Limited Slip Differentials" or similar

Cheers
DD

 

GL4 is specified for manual transmissions with yellow metals ( usually the brass syncro rings) and GL5 has the additives for limited slip.

As far as I know all V12's have limited slip and it was optional for certain markets on 6 cylinder cars. For example, in Canada an XJ6 will not have limited slip, while a Sovereign will.

 

So, Jagboi, are you saying that my Canadian 1984 XJ6 Sovereign has an LSD?

 

It should have, that was standard on Canadian Sovereigns.