On Mon, 4 Oct 2004 ortfamily@xxxxxxx wrote: > I like to keep the operating temperature of the engine at 175 to 190. Higher temperatures can cause knock, and the under-hood temperatures rise. Cooler air and fuel are more dense, so keeping the under-hood temperatures down is a plus. Higher under-hood temperatures also take a toll on the battery, hoses, belts, oil, and the paint on the hood, and will also affect your interior temperatures. The factory probably used a 195 as a compromise to sell in all climates, and likely used higher temperatures when they were first thinking about pollution. My cars seem to run better slightly cooler. With a 170 degree running temperature, I get adequate heat from the heater if the temp drops to freezing and I chose to drive it. If I get stuck in traffic on a hot day, no problems with overheating. Works for me, maybe something else will work for you. Yeah, combustion chambers and cooling systems like "high" temperatures, but nothing else under the hood does.