coolant flush/refill

You could add an equal amount of undiluted coolant to cancel it out.

what i am trying to find out is why the system will not take more than one gallon. the reservoir is still full and where radiator cap is, it is up to top as well. attempts to add more, just overflows. i am concerned that trying to run engine to circulate through system will potentially cause damage if not enough water is in there. all i am trying to do at this point is continue the flush, re-drain then fill completely with 50-50 to complete the process.

Okay, so go ahead and drain it. I do not see what the problem is. When you fill it you may have to run it temporarily to get the thermostat to open for it to fill all the way.

The system capacity when simply drained is about a gallon and a half. The twelve quarts refers to when the system is completely empty block and everything which only happens during a rebuild or when it was being assembled.

Here is a guide that will help you get the job done:

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

Has a video at the bottom.

Please let us know what happens.

Cheers, Ken

okay, I understand about letting car run so thermostat opens. do I then just keep adding to reservoir? When I tried to add to radiator through cap area, it started squirting out some.

Yes it can do that as it is heating up. The trick is to allow the engine to warm up completely, the thermostat will open then finish filling it.