Thermostat

[Livin' in the 80's]

Originally Posted by Dynomite

Depends on how much you drained......and depends on the concentration before and the concentration you now want (Low Temperature Protection).

I usually go for -20 deg more or less with Zs not driven in winter but under cover in shed/garage. If you are in warmer climate you may go a bit less antifreeze but anti freeze also does serve multiple purposes (anti rust, raises boiling temperature) in addition to obvious protection from freezing temperatures. I usually will refill with a gallon or a bit more of antifreeze and about gallon or bit less distilled water then top off white plastic overflow container under passenger headlight with pure antifreeze within an inch or two of top of that plastic reservoir. This is if you only removed a bit of coolant for Plenum Removal...I have TB coolant blocked so do not have to remove any coolant for Plenum removal.

Which white plastic reservoir I check after each of two or three heating cycles to make sure it is still topped off. I check before and after refilling/re-filling with 5 ball tester (I recall) and shoot for 3-1/2 balls floating (that is 3 balls floating and the 4th ball in suspension).

3 balls floating.......-10 deg F and +261 deg F
4 balls floating.......-25 deg F and +266 deg F

Now if you drained more coolant as in replaced water pump and radiator.....use more than 2 gallons approaching 3-1/2 gallons coolant more or less. If you removed engine and are now replacing coolant......use more than 3 gallons.....maybe approaching 4 gallons more or less of coolant. but do remember to go through several heating cycles after coolant replacement to top off with in 2 inches of top of that plastic coolant overflow under passenger headlight. You fill the coolant using the Top Black Reservoir just in front of the passenger side windshield under the hood.
OR

I am only replacing the thermostat. I would think that this will pretty much drain the entire system as the housing is mounted low on the frame rail. No?