Never Dry Start A Fresh Engine Rebuild!
Throttle Theory
1.2M views Β· 1 day ago
Why do mechanics slather brand new engine pistons in so much heavy oil?! π’οΈπ§ When an engine is completely rebuilt with brand new piston rings and freshly honed cylinder walls, the metal-on-metal tolerances are incredibly tight! If a mechanic were to put the engine in the car and start it "dry" without any lubrication, the massive friction would instantly score the cylinder walls and destroy the block in seconds. To prevent this, engine builders coat the pistons in a thick, sticky "assembly lube" or heavy-weight oil. Before ever firing the engine up, they rapidly spin the crankshaft manually. This forces the piston rings to push the oil up and down, perfectly coating the bare metal walls in a protective fluid barrier! This guarantees a safe start and ensures maximum horsepower!