Sea Foam is a petroleum-based engine cleaner that can be added to gas or diesel fuel to help remove carbon buildup and other gunk from an engine. It should be used every 2,000 to 5,000 miles.
Sea Foam can help increase lubrication by removing friction-causing carbon. It can clean interior engine parts that are not usually accessible because it is carried in fuel. Sea Foam is safe to use as often as desired, with some customers using it every time they fill up their tanks. However, the company recommends adding it about as often as an oil change.
It is a safe cleaner because it is petroleum-based, and it can be added to oil to clean other engine parts. This is usually a more-involved process that involves letting the engine warm up and then systematically removing parts and adding Sea Foam to those parts. This more-intensive process is recommended about every 10,000 miles for people who know what they are doing.
Sea Foam is anti-corrosive, meaning it can help the engines of vehicles that are being placed into storage. Since it works by circulating through the engine, it should be added early enough that most of the fuel tank is used. It also helps stabilize the remaining fuel so that the fuel does not cause adverse effects while the car is in storage. It is commonly used before storing small seasonal vehicles such as lawnmowers.