I have a 67 chevy C-10 with a 72 350 4-bolt main and I was having overheating problems so I figured out it was rad since everything else is new. I was running in city traffic on scorching hot day upwards of 225 degrees (not moving) with 185 thermostat. I bought an aluminum rad and dropped stat to 160. Problem solved I am running steady 155-160 on really hot day sitting in alot of traffic it went to 180. Can it be bad to run at a low temp like 155-160? Someone told me it is. If so I was going to put the higher 185 stat back in.