300bhp/ton

Been loosing water/coolant on my '99 Z28. I think it is coming out of the top of the coolant reservoir. It started doing this all of sudden and has never lost water before in the 8 years I've owned the car.

Water and oil look clean, no mayo. But I'm guessing this sounds like a head gasket issue?

Have I just been really unlucky. Motor has done 90,000 miles or so from new.

What's the best way to confirm if it is a HG and to figure out which cylinder head it is?

Exidous

iTrader: (11)

If you are pushing coolant and NOT overheating the head gasket has some blow by. Sometimes it just happens. It's a bit of work but not very expensive if doing it yourself. As long as the motor has not overheated to warp anything, you'll be fine.