Originally Posted by rick130
at least a side effect of better low temp performance oils, particiularly full synthetic ester and PAO formulations is that they are more stable at high temps, mainly through the use of little or no viscosity index improvers. Castrol in Germany even went so far as obtaining esters derived from PAO's that are viscosity index improvers that mimic a base oil providing an extremely temperature stable fluid at any temp seen in a vehicle.
I believe their Syntrans gear oil uses this chemistry. It is the overuse of VII's in cheap mineral oils (and some not so cheap ones) for low temp performance, which as you rightly say we don't really need in Oz, that make makes them unstable at high operating temps.
When I killed my last race engine ten years ago trying to run it as an air cooled version it never seized, detonation melting a hole through a piston crown finally bringing me to a smoky stop.
When I stripped it the next day, nothing was salvageable, the bearings had melted, rods were blue, block was cracked through the webs, crank was blue, etc, yet it all still went 'round and 'round.
To me that was an impressive high temperature performance from my oil, which was a 10W-30 diester based synthetic.
