my water temp reads low for the first half hour or more, then gradually makes it to 40 c, what the... is my sensor bad? I am running sinthetic oil in it and it is supposed to run a bit cooler than normal but sheesh 40 c... it eventually gets up to 60 c if I am going 60 mph climbing a hill but then back down to 40 c when I am going 35. Any ideas?

Thanks

Tahoelobo...