I would hang on to it and the next time you change the coolant, change the block heater as well. If your's is over 20 years old it is bound to have corrosion on it. If you don't want to keep it I am pretty sure it will also work with a gasoline car - the part numbers are the same on fastlane for diesel and gas block heaters. Oh, by the way, I priced a block heater at the local stealership - $89 and they would have to order it. I got mine for $44 off ebay - minus shipping. Same block heater. Someone will get a deal if they buy yours.....