You must do this while the car is in a well-ventilated area since the process will usually create a lot of smoke. Vehicles with automatic transmission should be kept in park. Vehicles with manual transmissions should be put into neutral, and the parking brake should be applied throughout the process.
On most vehicles, the best option will be the vacuum line from the brake booster PCV. Since different vehicles are set up in different ways, you may need to choose a different option. If in doubt, seek a professional opinion before attempting this method.
If using the brake booster hose, disconnect the hose going to the manifold. The check valve should remain on the hose going to the brake booster, and you should not allow Seafoam to pass through the check valve during this process.
If necessary, position a funnel in the opening of the hose and pour the Seafoam in through that. The manufacturer recommends against the practice of drawing Seafoam into the hose using suction.
You will probably see heavy white smoke coming out of the tailpipe. This is normal and should not be cause for alarm.
The longer you wait, the deeper the Seafoam will sink into the engine. Regularly maintained engines may only need a 10-minute wait, but for engines with a lot of suspected buildup, a full 30-minute wait would be better.
Drive legally. If possible, go on a road where you can reach speeds up to 60 MPH (97 km/h). This is best done at night or during another time when traffic won’t be an issue since your tailpipe will produce a lot of smoke. Once the smoke stops, the engine is clean and the process is complete.
Adding Seafoam directly to the fuel tank will provide a variety of benefits. It can clean deposits left behind in the fuel injectors, thereby making your vehicle run more smoothly. It can also control moisture buildup in the fuel, stabilize the fuel, and lubricate the upper cylinders.
When filling the tank, make sure that you leave enough room in the tank to add the calculated amount of Seafoam afterward. While Seafoam can technically be used with any octane gas, it is recommended that you use it with 91 octane or higher. Fuel with a higher octane number requires a greater amount of heat and compression to ignite, leading to improved performance. The Seafoam can provide a greater benefit to the vehicle under these conditions, as well.
Pour the product slowly to avoid spills. Using a funnel will also help prevent spills. Due to the design of the bottle and the position of the fuel tank opening, it is nearly impossible to pour Seafoam directly from the bottle and into the fuel tank without the use of a funnel.
As you drive, the Seafoam should mix into the gasoline, improving the quality of the gasoline and cleaning the fuel injectors at the same time. Try to run this tank of gasoline until the vehicle is nearly empty to maximize the effectiveness of the Seafoam. After completing this step, the process is complete.
You’ll be adding the Seafoam directly to the oil in your vehicle. Since Seafoam is made of petroleum, it is safe to mix into the oil and should not cause any damage to the vehicle. When used in this manner, Seafoam will re-liquify old fuel and deposits, clearing out the carburetor bowl and jets in the process.
Adding room temperature Seafoam to burning hot oil can shock the carburetor valve springs and damage your vehicle.
Consider using a funnel to pour in the Seafoam. Doing so is not strictly necessary, but funnels can help reduce the threat of accidental spills.
You should get the oil changed once you have driven a distance between 100 and 250 miles (160 and 402 km). Seafoam is a potent additive, so the oil filter can struggle and the quality of the oil can degrade after this distance. After driving the car and changing the oil, the process is complete.
