1991 Buick Lesabre thermostat temperatures

There are 185 and 190 rated thermostats as well, just more rare. Lowering it from 195 to 180 during summer time will not hurt anything. It's actually a very common exchange. By allowing the coolant to flow at a cooler temperature than the stock 195 thermostat, a replacement thermostat will keep the engine temperature cooler than stock. As we all know, cooler air is more dense and will make more power. Also, by keeping the pistons, heads, cylinder walls, etc. Cooler, you will reduce or eliminate "hot spots", which could prematurely ignite the fuel and cause detonation and pinging.