There always seems to be a bit of confusion regarding which kind of coolant to use in today's diesel engines. This was made even more evident by Spartan's change to a new coolant in the 2007 model year. Following is some information to hopefully remove some of this confusion.
Diesel engines are prone to
cavitation of the cylinder liners. These liners are generally considered "wet" liners in that they allow the engine's coolant to directly contact the outside of each liner, which promotes better heat transfer than a "dry" liner. These liners are pressed into the engine block and use o-ring seals to prevent leakage of the coolant into the oil pan. The high frequency vibration of these liners causes air bubbles to form. When these bubbles burst, the coolant shoots at the liner like a water blaster and leaves a pit. If allowed to continue these pits become pinholes and you'll have some serious engine rebuilding on your hands. This scenario is referred to as "cavitation" (which can also be defined as "putting holes in your wallet
").
To prevent cavitation, special coolants have been developed. Regular automotive "green stuff" or even the pink "Dexcool" variants just won't cut it. You need a coolant designed for heavy duty diesel engines with
Supplemental Coolant Additives (SCA). A very popular coolant was Peak's
Fleet Charge, which featured SCA additives. another popular coolant was Fleetguard's Fleetcool. These coolants were designed for heavy duty diesel engines, such as in motorhomes. They initially come charged with the proper amount of SCAs. However, after a while these SCAs, which prevent cavitation, wear out. Therefore you need to check your SCA levels every 6 months by dipping some test strips into a clean sample of coolant and verifying the colors on the test strips with the master chart. In the event that the SCA levels are low, you can add a can of SCA additives to renew your coolant. This is just a part of maintaining a heavy duty diesel engine's cooling system.
Another coolant is also introduced by Fleetguard. This is the Fleetguard
ES Compleat EG. This coolant is blue instead of pink. It is a better coolant in that it is extended life and uses a different additive package that relies on other chemicals rather than borates to accomplish liner protection. However, it is considered an SCA based coolant. While the additives may last longer, you'll still need to check them and add the appropriate SCA additives when required.
This brings us to
coolant filters. Normally filters do just what they say they do - they filter things out of the oil, fuel, or water. In the case of coolant filters though, things get more complex. The filters are packed with timed release SCA agents. As the coolant passes through the filter, the filter will release small quantities of SCAs over time. This will help to minimize having to manually add a can of SCAs later. Not all RVs will be equipped with coolant filters.
There is another type of coolant that has been recently introduced. The 2007 Spartan chassis now come with a reddish colored
Final Charge coolant. If you have a 2007 Spartan chassis you'll notice a decal warning that the system is filled with Final Charge and you should not add other coolants to it nor should you add any SCA additives to it. Final Charge is a departure from traditional heavy duty coolants. It features an
Organic Acid Technology (OAT) formula that does not require SCAs. There are no silicates, borates, nitrates, phosphates, or anything else that affects liner pitting. The real beauty of this coolant is that you don't have to check SCA levels every 6 months. The coolant is good for 600,000 miles or 6 years. It does require an automatic addition of a can of extender at 300,000 miles or 3 years to achieve this. You also do not want to use SCA filters with this coolant because they not only are not necessary, but can be detrimental to the OAT coolant. If you add the old SCA based coolant to the new OAT coolant it will accept a 25% contamination ratio but after that it's time to flush the system and replace with the proper coolant.
The biggest problem is that it's not always easy to find Final Charge coolant. Most truck service centers handle the popular Fleetguard line. Fortunately, Fleetguard makes a number of coolants. In addition to the pink Fleetcool and blue ES Compleat SCA based coolants, they also have an OAT coolant -
Fleetguard ES Optimax.
ES Optimax is another OAT coolant. It features virtually the same benefits as Final Charge and has the same extended lifetime. It too is a reddish colored coolant but the big advantage is that it's totally compatible with Final Charge and it's more readily found at truck service centers. Fleetguard is also a division of Cummins so you can be assured that there are no compatibility issues with Optimax.
Either system will work. Whether you choose to run the SCA based coolants or the newer OAT coolants you'll get adequate protection for your engine. The newer OAT coolants do have some advantages and benefits though, mainly in reduced service by not having to check SCAs and longer intervals. You won't even have to think about it for 3 years. That'll give you more time to enjoy RVing rather than maintaining your coach.
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