SeaFoam Engine/Motor Oil Treatment: Does It Work?

SeaFoam Engine Oil Treatment On 5th Gen 4Runner

Detailed Report, Review, Overview & Findings

I’ve heard about SeaFoam treatment and have always wondered whether the claims were real. It even says that we should be adding 1-1.5 ounces per quart of oil a few hundred miles before an oil change. What could that possibly do, though?

So, I set out to find out how well (if at all) this stuff works with cleaning and quieting the 4Runner’s engine. The process was simple enough and required no special tools. After adding it per the instructions, we inspected the oil and compared it before and after the treatment.

Find It Online:

Treatment Process

SeaFoam Engine Oil Treatment 5th Gen 4Runner - Crankcase Testing

Tools Required:

  • Paper towel or rag
  • Measuring cup or funnel (optional)

SeaFoam is petroleum-based, so it is safe to use in oil and knocks loose gunk and build-up inside of our engines. This loosens build-up from lifters, the crank, piston rods, and other internal engine components. To do so, the vehicle needs to be driven with the additive for 100-300 miles before an oil change.

My 4Runner gets oil treatments every 5,000 miles or less depending on how much wheeling I’ve been doing. The current oil has roughly 4,925 miles on it, so it’s time for a change. We need to run out to Palm Springs, run a few errands, and come back. This puts us right about 275 or so miles. Perfect.

The 5th Gen 4Runner has a 6.6 Quart oil capacity (including the fuel filter). SeaFoam recommends 1-1.5 ounces per quart, so we will use half of a 16oz can.

A few pointers with application:

  • Make sure your engine is not too hot and open the hood
  • Locate and remove the oil filler cap on the driver’s side of the vehicle
  • Using the measuring cup, measure out 8 ounces OR pour half the 16 oz. can directly into the oil filler cap using a funnel.


SeaFoam Motor Treatment Results - Oil Color On Dipstick

After driving the necessary miles to allow the SeaFoam to do its job, I compared the visual condition of the oil. As a baseline, we have zero mile, brand new Mobil 1 engine oil on the left. The middle is the untreated motor oil with 4,925 miles of use. Finally, on the right is the 8 oz. SeaFoam treated motor oil with 278.3 additional miles.

For consistency, the two used engine oil samples were taken with the engine at a warm operating temperature. As you can see, the SeaFoam did free up quite a bit of engine deposits and grime. This was impressive to me. I have been using this product for my fuel systems for years and still can’t believe the results. For reference, my 2019 SR5 Premium had 50,126 miles before this experiment, so it’s got a fair amount of use.

The lifters did get quieter and that is about the only noticeable difference besides the condition of the oil. There was no noticeable change to power or fuel efficiency.

Final Thoughts

SeaFoam Engine Oil Treatment Test

Pictured above is the sunshine test of the oils. I took a small amount of the pre-treated oil and put it in the bag. Once I got back from my trip, I swabbed the oil on a piece of white paper to do a clarity test.

  • Brand new (far right)
  • Untreated oil with 4,925 miles (middle)
  • SeaFoam treated oil (far left)

In conclusion, SeaFoam works great. So, I will also be using it in the crankcase of my 3rd Gen 4Runner and other vehicles. That being said, I would not treat it before every oil change. That seems a bit excessive; 1 to 2 times a year seems more reasonable. At around $5 per treatment, it’s cost-effective, too.

Good luck, and happy trails!

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5 months ago

How would this work with the MSC installed? Do you think it would help or could cause damage? Thanks!

5 months ago

perhaps an oil analysis from labs like Blackstone will help further decode how much it helps.
For instance, send a sample of untreated oil with 5k miles, a sample of treated oil at 5k mark, and a sample of post treatment oil 5k miles later. With 5k miles on each sample it should tell how much it helps!

5 months ago

I use seafoam in all my equipment. Pressure washer, 4Wheeler, weed eater, chainsaw, log splitter, tiller, and vehicles. Works great.

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