Technically the blue stuff is compatible with the green. The green coolant that you are using is Fleetguard Universal EG
, which is an Ethylene Glycol based coolant designed for heavy duty applications. However, it's a not a long life coolant. The blue stuff that was added is Fleetguard ES Compleat EG
, which is an extended life coolant. Unlike the pink Fleetcool (extended life) or the green Universal coolants, the blue ES Compleat has a different makeup of silicate reducing additives and replaces boron and some other silicates with some other additives. I don't have access to my notes but there were three major components that were replaced. Technically, Compleat does mix with the other coolants but your additives won't get along all that great and you'll have to pay very careful attention to your chemical makeup by using the test strips frequently to prevent liner pitting. For more details on diesel engine coolants I'd recommend you visit the RV Tech Library. Check out the Diesel Engine Coolants
page and follow some of the links.
Finally, if you are going to dump the stuff and replace it, which is probably about due anyway, I'd seriously consider going with the Fleetguard Optimax
coolant. This stuff is red-orange, yet another color
, but it is the best thing on the market. It's an Organic Acid Technology (OAT) coolant. OAT coolants do not require checking of SCA levels because OAT based coolants use organic acids, which don't have any liner pitting tendancies to worry about. Plus the organic acids don't eat aluminum like all the other coolants do so you'll get less corrosion in aluminum engine parts and radiators. They are good for 6 years or 600,000 miles and only require adding an extender at 3 years or 300,000 miles to accomplish that. It's the best coolant you can get for your coach and it's made by Fleetguard, which is a division of Cummins so it's available at any place that services Cummins. Plus Optimax is certified for virtually everything from your Prevost to a water cooled lawnmower.
I'm running it in my Cummins ISL and as soon as winter leaves I'm converting my Onan genset over to it too.