Charliebrown: 12L/100??! That's HORRIBLE! My VTi-R (1994, 150K) gets 10L/100km or better with quick driving and all suburban. If I do a long trip for half the tank I get about 7.7L/100km.

Also, why did you come in here asking for our help then tell us off when we give it? I'll second what others have said: Your mechanic is a nutcase - he should be quite alarmed that your car is running cold, especially if you ever drive it spiritedly. The fix should be easy, and what other problems could it possible cause? I like the attitude towards maintenance though "Oh my brake pads are worn out, but I'm not gonna fix it because I heard it can cause other problems". Do you REALLY think leaving the engine running cold would cause LESS problems than a fix?

P.S. Honda did mine five years and 70,000kms ago, and it's been absolutely fine ever since. Get it done - it's not expensive. And if it's your gauge, you should get that fixed too. You really wanna know when your car is overheating.