I was going to mention Evaporust. It is great stuff and won't harm the aluminum pistons. When it get really black the fluid is done. If you have to use some force on the pistons, apply the force on the outer edge, maybe with a socket.


1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed


My Chevy Master 4 Door is on the Road!