How long can you leave Sea Foam in your crankcase without driving your car? [SOLVED]

Thanks for the question! You can leave Sea Foam in the crankcase as long as you want – even until your next regularly scheduled oil change. It’s made with 100% safe petroleum ingredients that can’t harm seals or other parts.

We recommend adding Sea Foam to your crankcase about 100-300 miles before your next oil change. That gives the Sea Foam enough time to circulate and clean, and it allows all the reliquefied oil residues to be drained away with the old oil when you change it.