Rick's Free Auto Repair Advice

Should I Seafoam my engine?

How to Seafoam my engine

What is Seafoam engine treatment?

Seafoam is one brand of engine treatment. The manufacturer lists three ways it can be used;

• poured into the crankcase to remove crankcase deposits,
• poured into the gas tank as a fuel injector cleaner, or
• sucked into a vacuum line as an upper engine or top engine cleaner.

According to Seafoam engine treatement’s MSDS product safety sheet, it’s comprised of three liquids;

Pale Oil 40-60%
Naphtha 25-35%
Isopropyl Alcohol 10-20%

So you’re looking at a product that contains a lubricating oil, a solvent, and alcohol. All three products can act to break up engine deposits. That’s what it claims to do. So far, so good.

Seafoam engine treatment as an engine cleaner

If you add Seafoam to your oil, it can dissolve sludge buildup and deposits in your crankcase. Sounds good, right? Well, towards the end of this article I discuss the dangers of using chemical cleaners to remove sludge building in your engine.

Seafoam engine treatment added to your gas tank as a fuel injector cleaner

The two most effective fuel injector and fuel system cleaners are polyisbutylamine (PIBA) and polyetheramine (PEA). Seafoam doesn’t contain either of them. The Naphtha and alcohol components can act as solvents to clean deposits from fuel injectors, but they’re really not the best cleaners for fuel injectors or carbon deposits. In fact, I think they’re really obsolete technology compared to the most effective cleaners available today.

I’m not sure how the Pale Oil helps clean fuel injectors, but keep in mind that Seafoam engine treatment claims that their product can be used in multiple ways, so as a fuel additive, perhaps the Pale Oil rides along for free and burns like ordinary fuel.

Seafoam engine treatment injected into a vacuum line to perform top end cleaning

When added to the gas tank, Seafoam engine treatment is applied to the back of the valves by the fuel injectors (in non-direct injection vehicles). In a direct injection vehicle, Seafoam doesn’t work at all to clean intake valves when it’s poured into the gas tank.

But when used in a vacuum line, Seafoam engine treatment does come into direct contact with all the internal components located in the intake manifold. So the solvents have the potential to contact and clean valve stems as well as the back of each intake valve. Again, I don’t think they’re the best cleaners to use, but they do clean.

Now let’s compare the chemical makeup of Seafoam and other products that claim to clean fuel injectors. I’ve picked some popular brands

The first two products on the list are multi-purpose cleaners Seafoam engine treatment and Gumout Multi-System Tune Up. You’ll see that they’re also oils, Naphtha, and alcohol

Sea Foam Motor Treatment SF-16, SF-128, SF-55 (Sold in bottles at retail stores)

MSDS contents of seafoam

Seafoam MSDS


Gumout Multi-System Tune-Up (Sold in bottles at retail stores)

Gumout Multi-System Tune-Up MSDS

Gumout Multi-System Tune-Up MSDS


Next we have products that are marketed specifically as fuel system cleaning products

Chevron Techron Fuel Injector Cleaner (Sold in bottles at retail stores)

Chevron Techron fuel injector cleaner

Chevron Techron Fuel Injector Cleaner MSDS

Chevron Techron Concentrate Plus (SC) (Sold in bottles at retail stores)

Chevron Techron Concentrate plus

Techron Concentrate Plus (SC) MSDS


Chevron TECHRON Bulk Gasoline Additive (added as a fuel injector cleaner at bulk storage sites)

Techron additive

Chevron TECHRON Bulk Gasoline Additive MSDS

Gumout All-In-One® Complete Fuel System Cleaner (Sold in bottles at retail stores)

Gumout fuel system cleaner

Gumout All in One complete fuel system cleaner MSDS


Lucas Deep Clean™ Fuel System Cleaner (Sold in bottles at retail stores)

Lucas deep clean fuel system cleaner

Lucas Deep Clean™ Fuel System Cleaner MSDS


Royal Purple Max-Clean Fuel System Cleaner & Stabilizer (Sold in bottles at retail stores)

Royal Purple Max clean

Max-Clean Fuel System Cleaner & Stabilizer MSDS


STA-BIL fuel stabilizer (Sold in bottles at retail stores)

sta-bil fuel stabilizer

STA-BIL fuel stabilizer MSDS

ACDelco Upper Engine and Fuel Injector Cleaner (Sold in bottles at GM dealers and online)

ACDelco upper engine cleaner

ACDelco Upper Engine and Fuel Injector Cleaner MSDS


As you can see, each product has a different chemical mix, ranging from distilled petroleum products to polyether amines (PEA) and glycol ethers and aryl alcohol. As you go from a general multipurpose cleaner like Seafoam and Gumout Multi System tune up, you’ll see the ingredients change from light oils and Naphtha to PEA, glycol ethers, trimethylbenzene and proprietary products. Keeping in mind that all Top Tier fuels require fuel injector cleaners, it’s worth reviewing the Chevron Techron bulk product that’s added at the fuel depot prior to deliver to the gas station.

Back to Should you seafoam your engine?

In my opinion Seafoam or similar products added to a tank of gas won’t hurt your engine, although I’m also not convinced that the light oils and Naphtha based products do much good. I think if you’re going to add a gas treatment to the tank, a product containing polyisbutylamine (PIBA) and polyetheramine (PEA) might perform better.

Next comes the issue of whether you should inject Seafoam or other top engine cleaners like the ACDelco Upper Engine and Fuel Injector Cleaner cleaner into a vacuum line. Here’s where I have a problem with the technique.

Injecting Seafoam into a vacuum line can destroy your catalytic converter

In a vehicle equipped with a MAF sensor, all incoming air is metered by the MAF usually mounted right after the air filter. As soon as you remove a vacuum line on a MAF equipped engine, you introduce UNMETERED air. The PCM sees the unmetered air by way of the pre-cat oxygen sensor suddenly going lean. The PCM responds by adding fuel.

Now you inject Seafoam or Gumout Multi-Tune product into the intake vacuum line along with the added fuel. Whether you’re cleaning the valve stems and interior of the intake is almost irrelevant at this point because what you’re also doing is dumping extra fuel and cleaning solvents into the catalytic converter.

This injection technique can cause your catalytic converter to overheat and self destruct. Yup–a $1,000 repair bill because you tried to clean your engine.

So what can you do?

First, you can try another injection method. The ACDelco Upper Engine and Fuel Injector Cleaner product recommends injection by atomizing the product into the air intake duct, not a vacuum line. That way you’re not getting unmetered air past the MAF. To do this you can buy the product in an aerosol can or buy an atomizer canister. Load the liquid into it and pressure with compressed air. Then, spray the product into the air snorkel so it’s measured along with incoming air. As the product burns, the pre-cat oxygen sensor notices the richer mixture and the PCM cuts fuel trims. In my opinion, this is the only safe way to inject a top engine cleaner without destroying your catalytic converter. However, some car makers still warn against this method. They’re concerned that however much the PCM cuts back on fuel trim, this additional fuel may be too much for an exhaust mounted catalytic converter to handle.

For top engine cleaning, I prefer the ACDelco Upper Engine and Fuel Injector Cleaner atomized into the air duct prior to the MAF sensor.

Finally, there’s the issue of using engine flush solvents in the crankcase.

I have to honest, I’m not a fan of this at all. My opinion, of course, but if you take care of your engine with regular oil changes, you don’t need to add any solvents or flushing agents. I believe they do more harm than good.

When poured into the crankcase as an additive, these chemicals tend to loosen deposits that can break away and clog oil galleries, hydraulic lifters, and the oil filter. So you think you’re doing your engine a favor and the next thing you know, you’ve got a lifter tick or engine knock. Instead, I would opt for more frequent oil changes if you’re at all concerned about deposits or sludge in your engine.

Adding Seafoam to your crankcase isn’t as dangerous as getting a full-on engine flush, but it can still dislodge sludge deposits and damage your engine. It’s not risk free and there are better ways to clean your engine in my opinion; like changing the oil more often

©, 2015 Rick Muscoplat


Posted on by Rick Muscoplat

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