All ActivityMost RecentMost LikesSolutionsRe: Breakdown InformationI recently broke down in Mazatlan. The problem was an overheating engine. It turned out that radiator fan stopped working. After several phone calls to Freightliner, I was advised to drain the Dexron III ATF in the hydraulic reservoir, flush the lines and replace the ATF with 15-40 motor oil. It worked! It seems that, in some applications, ATF is a little too thin to turn the fan properly. In my case, the fan stopped but I was able to get it to run again by starting it by hand. It would then run but only at about half-speed...not enough to cool the engine properly. After changing out the ATF for 15-40 engine oil, the fan ran like a wildcat. It seems that some applications need a slightly thicker hydraulic oil to work properly.