Background on that question: My '93 FD is a dedicated autocross car fully prepared to SCCA ASP rules. This past season I switched from running 50:50 water/antifreeze to straight water with HyperKuhl additive for its better heat transfer properties. It made a noticeable difference.

The car spends its summers in the Chicago area and then I trailer it with me to the Austin, TX, area for the winter, so it will be below freezing for the initial part of that trip. I could drain the water/HperKuhl mix and replace it with antifreeze and then when in Texas drain the antifreeze, flush the system with the HyperKuhl SuperFlush, and then add back the water/HyperKuhl coolant.

I'm lazy, it would be much more convenient to just drain the water/HyperKuhl coolant, travel with it empty of coolant, and replace it in Texas. But I'm concerned that there may be some cavity in the system that would not fully drain and be subject to freezing and causing damage, thus the question.

TIA, Philip

 

Water freezing is a problem where there's no room for expansion. It will take the path of least resistance when expanding.

A totally full coolant system has nowhere for the coolant to go, so it pushes against the inside of the motor. If it's drained and only has like 10-20% of the system with water, it's just going to expand into the voids.

But to be on the safe side I'd just get a jug of Prestone and dump it in there - not even bleed it, just fill as much as you can. That would be good peace of mind.

Dale