Hi, new to the forum. I tried some searchs and did not find any answers but I may have missed it, sorry.

I have a 93, F150 with a 5.0. I have drained the coolant twice and only seem to get 8 qts (50/50) back into her, the manual calls for 14. I dont get it. She doesnt overheat and actually only ever gets to the "O" in normal. When draining, I know the thermostat opened cuz I ran it with the system open to completely flush the system and the temp got up to "m" and I saw some steam before I shut her down. After filling with e gallon of coolant and a gallon of water, I ran her for about 10 miles, so I am sure the thermostat opened up. She runs fine. Any thoughts?

 

The capacity for the entire cooling system is 14 quarts. Not the radiator. You still have the water jackets in the block and the heater core, plus what's in the hoses and the water pump. If it's not overheating and the gauge reads normal, why are you even bothering with it?