Is pure coolant ok to use in my situation?

Ok, I used to work at a coolant manufacturing place.. 60/40 is the best mixture make sure it has SCA additives or you need to add a bottle!!!!
60% coolant
40% DISTILLED WATER, not tap water.

 

And check your SCA level afterwards. There are test strips for that. You could probably just start with two bottles-pints of an coolant additive.

 

See if you find a jug with a temperature chart on it. The 50-50 mix actually has a lower freeze and higher boiling temp than straight coolant.
Straight coolant is thicker. The silicate level is higher. Both of those could be a problem.

 

I did some math, look out !!! I’m assuming you have a total of 10 gal antifreeze, and were also already at 50/50. Now you’re at 75/25 . If you drain 3,5 gal out and add 3.5 gal of distilled water, you should end up with 50/50. I’d do 3 gal. Should put you around 60/40.Add another 1.5 gal to the 3 extra gallons and keep for emergency in side box. I would honestly flush and fill, as cheap as antifreeze and distilled water is. Best thing is put final charge antifreeze along with a pre charged on demand dca additive release water filter. And be done with it for a long time. Changing filter yearly. Tractor Supply sells final charge pre-mix. for $11.00 gal. Already has proper additives for dca levels.