So, Im in the middle of changing my Opti and when I pulled the waterpump I lost almost 2 gallons of Dexcool. My question is how much more coolant is there in it and should I try and flush it now and go with the Green stuff? If so how to flush it and how much Green kind would I need? Do I mix 1 gallon green stuff with 1 gallon distilled water? Or should I just put some of the Dexcool compatible Prestone 50/50 stuff in? My Dexcool coolant was very clean when it came out, so its really not in bad shape.

 

You'll still have some in the block but I don't know how much. There are 2 drain plugs; one on the driver's side by the engine mount, the other is the knock sensor.

 

NOOOO green stuff. GM has a seperate coolant for a reason.

I believe total coolant capacity is 15-16 quarts or so. Use a 50/50 mixture of dex-cool and distilled water. When was the last time the system was flushed? If you can't remember, you can't go wrong doing it.

 

I flushed mine out completely and replaced it with non-Dexcool green antifreeze mixed with distilled water.

 

I have been using the green stuff for over 5 years no problem.