Overheating super quick

awesome, right ive put the old thermostat back in and followed jonnys guide and it runs sweet now, except for the white gunk on the oil filler cap.
Any ideas, im not sure if its the head gasket?? theres no oil in the header tank,
when i start it up the oil light flashes for 20-30 secs.
thanks again
Jim

dont worry about a bit of mayo on the oil cap will just be condensation (short journys dont help) take it on a good run that will most probably cure it.

anybody know the outcome of this?