I took my truck to get an oil change, and the guy that was doing the oil change told me that I was a gallon low of cooling. I did notice while I was driving the heat would blow hot, and when I slowed down and stopped at a light it gets cooler. The guy topped it off with cooling, it seemed to be working fine for about a week. Now it is doing it again. My guess is I'm low on cooling again. My question to you fokes is why am I losing cooling??? Also, I don't see any cooling on the ground but I occasionally smell cooling when I walk pass the truck.

 

More than likely your radiator is leaking at the hose. The clamps for em have changed/upgraded since new. It's typically a pretty slow leak, & hard to notice. It's happened to most of us. I would rarely see anything on the ground either, as it would run down hoses/rails/etc.. Finally I saw a few drops on the ground, kept an eye on it, kept seeing it.... took it in, & had the hoses replaced. It was too late in my case as, a short time later, I had the radiator replaced...

It's a common issue/problem

 

I agree, check the radiator seams.

Don't run low on coolant. Causes cavitation and EGR cooler failures.