djpauls Report post Posted January 4, 2013 2001 Dynasty with Cummuns 350 ISC. Cooling system flushed and Extended Life OAT based coolant installed November of 2010. Coolant filter replaced with SCA dispensing filter October of 2011. Radiator replaced and 5 gallons of non-OAT based coolant used to top off system February of 2012. Cummins dealer added additional SCAs when serviced September of 2012. I realize that there are all sorts of things wrong with this picture but my question is when should I again flush and fill the system and should I continue to monitor for SCAs? Share this post Link to post Share on other sites
wolfe10 Report post Posted January 4, 2013 Flush and fill with one or the other-- the two chemistries are different. I favor the new OAT-based coolants, as they have twice the life and do not require testing and adding SCA's. Remember, on a linered engine like your Cummins C, the proper coolant chemistry is REQUIRED to keep cylinder walls from eroding. BTW, if you go with an OAT-based coolant, the filter you use is a "blank". A blank has zero units SCA, but is a filter. Share this post Link to post Share on other sites
