My truck has been running really cool lately, like the line right after 130*. I just have a cheap 180* thermostat that I don't remember where I got it from. 1. Is the most likely culprit the thermostat being stuck open? 2. If it is, when I replace it, should I stay with 180*, or revert back to stock? (Ive heard mixed opinions) 3. Is there a recommended brand of thermostat?

 

engine temp running at 130-150 is a bad t-stat.
get the Stant Superstat brand for about $15.
if you don't have a constant check engine light with the 180, i'd stick with it. i like to see the engine at 180-190 instead of 195-205.

 

Dont get a "failsafe"

 

I have a Stant Failsafe 180°. My truck never goes above 180 or below when warmed up. As for the issue with failsafes tending to pop often, I haven't had a single problem and I live in Florida.

 

ehh at least its a Stant, ive never had a problem with a normal stat

 

I've used failsafe in the past and haven't had any issues with them. What problems have you had with fail safe to make you dislike them?

 

stories of "Failsafe" t-stat failures are frequently posted on here. some fail in the open position like they are supposed to. a few fail in the closed position like they are not supposed to.