Strong akaline cleaners are responsible for the discolored castings.
For cleaning an engine without the ugly oxidation, use Prestone automotive antifreeze heated but not boiling. Keep engine completely submerged at all times. The antifreeze should be diluted 50-50 like you were going to use it in your car.
Add water to the mixture as the level drops to keep the engine submerged or you will have a water mark arou d your casting.
A potpourri pot works best. Takes 24 hrs typically .
Last edited by w8ye; 05-19-2018 at 12:24 PM.