Thanks for the info that was discussed here. While studying how to change coolant I decided to see what is written out there on the net. I had come to believe anti freeze (coolant) is almost as mysterious as oil. However, right up there for maintenance. I came across the below article which is very informative and might give direction to how I will pursue what product to use. Any comments will be appreciated. NOTE - the bold lettering is mine.
"The latest generation of coolants is refered to as Extended Life Coolant (ELC) and is a significant improvement over coolant technology of just 10 year ago. The majority of these coolants use Organic Acid Technology (OAT) to eliminate the constant monitoring of SCA levels. In addition to this low maintenance approach, they are longer lasting, and a far better coolant. The final benefit is that most of the OAT coolants are compatible with each other. OAT coolants do not use nitrite/borate salts or phosphate/molybdate additives as SCAs. Instead they utilize carboxcylic/fatty acids to handle those needs. The largest benefit is that the coolant is good for 6 years or 600,000 miles - whichever comes first. The only maintenance requirement is that you must add a can of extender at 3 years or 300,000 miles to replenish the additives. You do not have to monitor SCA levels any more because there are none so throw away those test strips. You do not add any SCA additives to an OAT coolant either so if you have converted to an OAT coolant and have a SCA filter, just remove it or replace it with a plain old filter without any additives.
But OAT coolants have many other benefits as well. Organic Acids are kind to aluminum. Traditional coolants tend to eat away at aluminum and you'll find corrosion and deposits in water pump housings after a while. Radiators, as well as their solder joints, are much better off with OAT coolants. Your generator set has lots of aluminum in its engine and OAT coolants will keep that system much cleaner and efficient than a non-OAT coolant. Finally, the fatty acids are actually good for your water pump and help keep it lubricated, which is just the opposite of the traditional coolants which rely on short term additives in the coolant to accomplish this. That's why it's not a real good idea to "extend" an extended life coolant because the additives do drop off as the coolant ages with use. OAT coolants don't have that issue and just need a quick shot of extender at 3 years to keep your RV's cooling system up to snuff.
OAT coolants are compatible with just about anything so you can use the same stuff for your engine as well as your generator. They are also cross-brand compatible. Peak's Final Charge coolant is an organic acid coolant and is currently used by Spartan in their chassis. Cummins' Fleetguard Division originally made an OAT coolant called Optimax but this has now been rebranded as ES Compleat OAT extended life coolant. Caterpillar offers it's own Cat ELC coolant, which also uses hybrid OAT technology. All three of these are 100% compatible so if you can't find one brand, you can go into any truck dealership and pick up one of the others at the parts counter. The majority of the OAT coolants are orange in color, although this can vary, so color alone won't determine OAT status. Shell's Rotella ELC coolant is more of a red in color. It too is an extended life coolant that can go 600,000 miles. However, it is not a true OAT coolant so don't go mixing this with any of the other brands of OAT coolants.
Diesel coolants have come a long way in recent years. Even if you don't have wet sleeved cylinders you can still benefit from the engine friendly OAT Coolants and the extended service intervals of any ELC coolant. Your engine will thank you for it."
