Oil brands for severe use, and racing?

[Ant]

This subject is probably more up to personal preference, I am curious to know what other Cobra owners use in their cars for hard use regarding Oil/grease manufacturer and type of oil and grease.

I have used Castrol RS 10W60 and found it to be extremely stable even when hot at above 250F, where as other oils dropped oil pressure like the Mono 50w racing oil, and synracing that I have used, I found these to be hopeless in my 600+hp BB, but having said that it was only temperature based relating to oil pressure, not sure of the lubricant value etc, so won't bag something I know nothing about!

Out here we have Castrol and Amsoil, who both make racing oils, and incidently Amsoil makes a nice 2000 synthetic racing grease, which interests me as I am about to do some final assembly of wheel bearings etc.
Also Redline oils and some other US manufactured oils available now.

Another thing that amuses me is some engine builders stipulate certain oils and say don't use synthetic oil with this camshaft, but use this premium oil brand and grade, and when I look up the oil its synthetic based or full sythetic anyway - confusing, it appears all the top line oils are synthetic one way or another.
Curious to know what people race with over in the US, I am actually a Castrol fan, but see very good write ups on Amsoil.

Ant