Reply With QuoteThats correct. In theroy the spec of VMX 80, Penrite Xtra lite, and Valvoline dura gear 75/85 all meet the LR spec, in practice they seem to provide different syncro performance this would be due to the additive package, I suspect that all would lube ok. The Caltex oil is in made to an LR spec for LR.
It's important to understand also that oils aren't oils and that in most cases quality synth oils are better than mineral oils ie Syntrans would be a supieror oil to Cal MT94 and would likly exceed the LR spec.
I run Castrol SAF XA 75/140 in my diffs, I could run normal 90 hypoid but choose to pay more for the synth for aditional high temp stabillity and extended drain intervals. Synth oils while rated to the same SAE weights are actually quite thin and flow better when cold. SAF-XA is has a reccomended drain interval of up to 300 000k in Eaton and Rockwell diffs (truck stuff), it also what Ford and Holden use as a factory fill in HSV and FPV cars, also used in V8 supa car Hollinger 6 speed boxes, Jag XJ220 Mercs at Le Mans etc.
For the Transfer case I run Penrite 1Oths 75/90 race diff oil but you could use Castrol syntrax. Again normal 90 EP would be ok as speced by LR.
To date my car has always run Valvoline dura gear in the main box but I have been considering Syntrans at the next change to see if cold changes in winter are any better.
For me I don't mind paying for some extra High temp stabillity of synth oils. The mate Brad just smoked his Disco box due to a slightly low oil level, worked it hard, the oil cooked, went black melted the first motion shaff bearing, layshaft bearings and stuffed the first motion gear and layshaft front gear. $1200 in bearings gears from MR automotive (LR list price from the layshaft cluster is $1300 alone)BY the way this box was only 20k old, so everyone go and check your oil this weekend.
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