So the only plugs I had to put in were -8. I normally run the 7. Will 1 degree colder affect engine temp? Primarly at idle. At idle engine temp will not get above 120. It loads up on fuel. Once it warms up it will idle fine until temp drops back down. The 8 were only installed temp. until i got the 7. Just curiuos. On the hose with less water flow temp goes right up normally. In water with more flow temp will not go up. I get about 5 psi of water pressure at 1000 rpm, and 10 about 1500rpm. anything above 2500 it is at 20psi. Does that seem normal? I have a factory merc dump valve so it'll never go above 20. Any opionions? thanks.