Hey guys, car is a 97 WRX - Standard that i know of, anyway these are the faults on the car

"losing a lot of coolant, especially on a long drive, lost power, an can smell petrol in the oil cap
plus the coolant in the overflow bit looks like its been mixed with oil or something"

what do we think, head gasket or worse?

 

That does sound like a possible HG fault. If you're losing water and can't find a leak, that's a good place to start.

 

I had that when my00 Uk turbo big end bearings went, apparently the hg was phone though. Is it rattling between 2-3k revs?

 

I would get a sniff test done.

 

sniff test? i've not seen the car, its my mates, just going off what he has told me

 

A sniff test also known as a tk test,co test,block tester works by sampling the air in the cooling system at the radiator filler,when combustion gas is present it causes the testing fluid in the tester to change colour.
Shamelesly stolen from another forum, seems to be the 1st step in determining HG failure

 

Sniff test, ie head gasket test