My gauge fluctuates from 165-180ish. I have good water flow and my risers and manifolds are not hot.(I can even touch underneath) My thermostat housing can also be touched and it is only warm so I am thinking my gauge is wacky. I have a 160 thermostat and my engine is salt water cooled. What should I run at? My gauge goes about 1/8 inch passed 170 degrees and then back to 170 or a little less then back up. I have a raytec temp gun and I want to check to make sure I am ok. Where do I check the temp? AT the sensor on the thermostat housing? FYI, It's a new thermostat also. I want the temp to STAY around 170.....I hate that it goes passed the 170 and back down, it makes me hold my breath until I see it drop then I'm ok....