With nine benefits for your engine’s oil and fuel system listed on the front of the can and at less than $8, this mystery liquid sounds too good to be true, but it isn’t.

Sea Foam Motor Treatment is an all-purpose fuel and oil additive that’s safe to use in both gasoline and diesel engines. Close to 80 years old, in use since the early 1940s, the Sea Foam name is synonymous with getting temperamental engines that are filled with some sludge or carbon or that have been sitting too long, up and running like new again.

Once only available in an 16 oz can and 1 gallon jugs, there are now a dozen variants of Seafoam including Seafoam in spray form, high-mileage Sea Foam, and a Sea-Foam treatment for transmissions.

What is Sea Foam?

While the actual composition is a secret, Sea Foam does have an MSDS Safety Data Sheet which lists Petroleum distillates, hydrocarbon-based solvent, and Isopropyl Alcohol as its three key ingredients. According to a post on Hildstrom.com, an older MSDS sheet (now unavailable) lists those ingredients as pale oil, naphtha, and as Isopropyl Alcohol.

Naptha and pale oil are petroleum-based distillates known for their degreasing properties and is where Sea Foam gets its sludge-fighting properties from. Distillates are good for the removal of heavy oils, grease, tars, and waxes. With a low surface tension, they are good at penetrating and cleaning small spaces.

Isopropyl Alcohol, used for engine treatments, is also known as Dry Gas or a liquid that absorbs water ,keeps it in solution and keeps collected water in fuel and oil systems from freezing. IPA is especially useful for engines that have been sitting for a long time and might’ve collected water with swings in temperature.

Since all these ingredients are petroleum-based, “the same basic petroleum chemistry as motor oil and gasoline already in your engine,” it’s safe to use in most concentrations.

When should I use Sea Foam?

Carburators are notorious for gumming up thanks to the residue modern fuels leave on the tiny jets and passages inside a carburetor. If not run hard enough, often modern fuel-injected engines suffer from carbon buildup in the upper-valve train. And, if you let your engine sit long enough, moisture can form and collect in the fuel system.

Carburetor or fuel injected, if you notice hard starts first thing in the morning, sluggish or jerky acceleration when you give it a lot of throttle, noticeably louder tapping and noise coming from the top of your engine (a tick-tick-tick sound as opposed to a marbles in a washing machine sound) your engine probably has fuel and carbon buildup that needs to be removed to restore performance and fuel efficiency.

Noteworthy is if you have a modern turbocharged engine, like these new Honda Civics with their 1.5L Turbos, and you honestly do not drive them a long time, only a few miles each trip, and you notice sluggish acceleration, hard starts, and, poor fuel economy, you most likely have carbon buildup and need to get it cleaned out. Sea Foam can do that.

Additionally, if you have small engines, like generators, lawn mowers, and chain saws, that are not running as smoothly as they should, Sea Foam can work wonders, too.

According to Sea Foam, the benefits when used in the fuel system include,

  • Helps your entire fuel system run smoother & last longer
  • Cleans fuel injectors & carburetor passageways
  • Cleans intake valves & chamber deposits
  • Lubricates upper cylinders

The listed benefits for the oil system include,

  • Safely liquefy petroleum residues that restrict flow and lubrication.
  • Clean oil control rings, vvt solenoids and actuators.
  • Dissolve and clean deposits throughout the crankcase including diesel soot residues.
  • Clean and quiet noisy lifters and timing chain tensioners and reduce diesel injector stiction.

And the benefits as a fuel stabilizer include,

  • Stabilizes stored fuel up to 2 years
  • Helps fuel resist evaporation
  • Preserves ignition vapors
  • Adds protective lubricity
  • Prevents gum & varnish formation

Does it work?

The short of it is, if your engine is genuinely suffering from a gummed up carb, carbon build-up, or has bad fuel from sitting around too long, Sea Foam works!

The internet is full of stories from Sea Foam users who use the stuff with varying degrees of success.

I came across this Reddit thread that backs up a lot of Sea Foams claims from self-proclaimed, unbiased users.

Reddit User Kurtis1 says,

I had an old 92 Chevy truck with a 350. It started making a ticking noise like a lifter wasn’t pumping up. I out some seafoam in the crank case and it fixed it after driving 20-30 miles. It is amazingly good at cleaning sludge out of a motor. Dump a can in your crank just before an oil change, your oil will turn absolutely black when you drain that oil.

On another Reddit thread, user DonaldFagen mentions that,

I put 1/3 in my oil and 1/3 in my gas on a ’93 Geo Prizm (120,000 miles). I ran it for 1000 miles… had oil changed. It cleaned up so much gunk I swear my mileage went up 3-or-4 miles a gallon.

A helpful review from Bree on Amazon reads,

I have an early 2000s Subaru with about 130k miles on it. I started encountering a rough idle in the spring of 2018. After trying a few usual suspects to no avail (cleaning the throttle body, changing the fuel filter), I shrugged and poured a can of Seafoam into the tank before filling it up.
Result 1: the rough idle disappeared (though this could have been a delayed effect of the other treatments finally kicking in). I was more impressed, though, by Result 2: my rate of gas consumption dropped 2.5 MPG, enough that I was using over a gallon less per week for the same commute. The can paid for itself in two weeks. I’m almost inspired enough to try the other advertised applications (putting it in the crankcase, or in the oil before a change).

And the mostly positive experiences with Sea Foam go on and on.

The way I see it, there’s little downside to Sea Foam. If you have a new-ish car and really don’t see any symptoms of oil sludge, carbon buildup, or rough performance, Sea Foam is more than just a placebo and you don’t need Sea Foam.

But, if you genuinely have rough performance, poor acceleration and efficiency, and strange noises from the top of your valvetrain, Sea Foam might be the cure.


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