Has anyone got thoughts on Prestone GM approved Dex-Cool antifreeze used in cars that sit alot, mainly our Vettes threw the winter? I herd that it can start to sluged up and plug the radiators and heater cores over time.
I put this stuff in after my heater core replacement and was wondering if I should flush it out again. I certainly don't want to replace the core again in a couple of years. Thanks for the thoughts............

 

I have some info, kinda long, re: Dex-cool that I can e-mail if you like?

 

I think the troubles with dex cool tend to stem from those who try to mix it with the green stuff. I'm pretty sure that if you flush your cooling system completely you'll be fine using Dex Cool. I use Dex Cool, but I don't let me car sit over the winter, so I can't say for sure on that.

 

Nope. Problem with Dexcool (Prestone/Texaco/GM brands) involves low coolant levels and hot spots mostly, and IMO. Green AF plates out silicants onto the metal surfaces, and will protect even with low coolant levels. Dexcool must be in contact with the surface to offer protection. Also seems sensitive to changes in state, i.e. steaming causes problems with the coolant.

Guys on classic car boards who changed over to DexCool (for reasons unknown to mankind), had problems with bacterial growth during down times. Seems the little buggers like the organic additives. Many reported finding pressure in the system after a couple months storage.

GM also does not recommend using DexCool on pre 94 cars. Speculation involves seal technology changes, location of the overflow tank, block hot spots and so forth.

If you run Dexcool make sure you test pH every couple of months and if it goes below 7.2 to 7.0 flush it (this informatin I got direct from a Texaco engineer). Never let the level get low. Run the overflow level at "full hot" when cold. Use a positive spring pressure Stant pressure cap to insure the vacuum vent valve is sealed at all times. Run a 50/50 mix and don't use the sealing tablets.

There is no advantage to DexCool other than the aledged longer replacement interval. I've never made two years in my truck. Dexcool is 90+% the same stuff as Green (ethelyne glycol), but the corrosion additives are vastly different. According to Texaco, it can be mixed with green, it just won't last 5 years. They also say it won't last 5 years in an engine that did not come with it stock.

Pete