I have just bought a new thermostat and rubber from the stealer (just under £20) and fitted it. Before my car used to heat up quite nicely and never really got past the first quarter of the gauge.
Since having the engine out and back in again its been useless at heating up. So i bought one fitted it today and within a few minutes from a cold engine started creeping up on the temp gauge.
I take it out give it a run and its sitting around the half way mark.
Is this too high?? Got it home left it running for a bit longer and the fan kicks in just over half way. Then cools it back down to just under half way.
What are your cars like?