Is it safe to add Sea Foam to the engine oil on an gas engine with over 250 thousand mile just to flush it out? [SOLVED]

Thanks for the question!

Yes, you can add Sea Foam Motor Treatment to the engine oil in a gasoline engine with over 250,000 miles. Sea Foam is 100% petroleum-based and won’t harm engine parts or components. Sea Foam works to gradually reliquefy old oil residues and deposits throughout the crankcase so they can drain away with the old oil when you change it.

I’d recommend using High Mileage Sea Foam for its extra cleaning strength. Add 1 oz of High Mileage per quart of engine oil, about 100–300 miles before your next oil change. Do not exceed 1 oz of High Mileage per quart of oil.

For an engine with that many miles, I’d recommend thinking about it as a gradual approach rather than trying to flush everything out at once. Add High Mileage to your oil before every oil change and, over the course of a few oil changes, it’ll gradually help clean things up.