This may be a bit of paranoia, but I'm starting to fret about my cars head gasket.

My last car had its blow three times in three years.

Two days ago I noticed white smoke coming out of the exhaust when revved, even after a good two hour drive, so it was warm.

The temp has never gone over half way, coolant and oil is clear but I have noticed a small coolant leak, the catch here is I'm using the aircon a lot so I don't know if that will have an impact.

I changed the coolant a couple of months back, as well as the heater valves so it's possible the leak is from there, but I can't see it or any evidence of it leaking from there.

What do you guys think? I've never owned a v6 before but can't see any external leaks.