I just did a flush and re-fill of the cooling system and was wondering if I should have changed the thermostat? It took exactly four gallons to top up even though I have read that it holds closer to six so I know there was some old coolant in the block. I used the Delo 50/50 premix. I have been keeping my eye on things and the new coolant looks as clear as when I put it in. I figured that upwards of two gallons still in the system would discolor it somewhat. Any thoughts? Kurt

 

If you're not having trouble with temp. fluctuations you should be alright. You wont loose that much coolant if you have to change it. You might want to check how cold the antifreeze will go if you're worried about cold temps before the next change. The way I did mine was to remove the lower radiator hose at the engine and jack up the rear of the truck until the engine is a little to the front of being level. I still could only get 5 gals. in mine by doing it this way.

 

My driveway is steep enough to elevate the rear of the truck to drain the cooling system pretty good so I'm ok there. I'm just wondering if I should have changed the t-stat. The temps seem normal after a week of driving and the fluid is at the proper level.