I've read that there is a front cover seal compatibility issue on the IDI (International) 6.9/7.3 engines when ran with ELC or other OAT coolant. I use standard IAT green with DCA-2 SCAs (Napakool or in an older coolant filter), or the purple Prestone Command precharged in mine. I did way too much research on this when I bought my '89 F-450-I actually used Pride 1000 precharged diluted with distilled when I bought it, but Pride seems tough to find now, believe they got bought out. Final Charge is ELC, but FLEET Charge is likely OK. I'm not running an aluminum radiator in it at the moment (although I do have a Spectra aluminum one in the stash in case I need it).