I recently got a new radiator and had a shop put it in along with some other stuff. When I got the truck back there was no coolant in the overflow tank at all so I drove it a couple more times (after checking if there was any in the radiator lol) and still nothing so I topped it off. A week later it was down about an inch so I thought it was leaking but found no evidence of a leak so I just added some to get it to the cold fill line (while the engine was cold) and now after driving a few times it up above the line about an inch. Is this normal? I like it on the line exactly so I can monitor if its losing any at all but maybe that's not the best way to do it?

 

The level should go up when the engine gets hot from the coolant expanding, then drop back down as the engine cools and the coolant contracts.

 

Hmm I only check it on a cold engine on level ground. At least I know its not leaking. Fixed my problem of trans oil in the coolant too

 

Mine doesn't seem to fluctuate up and down that much, but the reservoir is always empty and the radiator is always full. And it doesn't seem to have any leaks.

 

Outside temps will mess with you a bit

 

that's why it's called an "expansion tank" It's doing it's job... Not to worry.