poured in the gas tank. effective or snake oil? thank you for your time.

RR ... that and Stabil... been told it’s snake oil PLUS ... much like lots of Lucus products

Ive seen with my own eyes what seafoam can do so I’m sold on its value. Check the search feature and check it out. It’s good stuff if you don’t expect overnight results

Concentrated through a vac line that feeds all cylinders in a hot engine, let sit for twenty minutes, then start it up and blow all the smoke out. Noticeable differences in the cars we've done that had high miles and weren't running smooth.

I guess my question is what do you expect it to do? I have used it for older engines with sticking lifters, pour in the oil a few hundred miles before an oil change to help clean varnish, sometimes it works. Carbon build up in combustion chambers, induce into the engine, carb, throttle body or a vacuum port, yes it helps knock carbon loose. Never used it as preventive maintenance in fuel tank, but would not hurt. Just don't think it's a magic wand.

I had a V-65 Honda that the gas went bad and was showing signs of carb problems so I started it up with a small tank of new gas w/sea foam which seemed to clean the carbs out perfectly, it ran as good as it ever did after that. I don't think I would ever run it in the crankcase though

My intent would be to clean the carb or injectors. Sounds like running a can with a small tank of gas might be worthwhile. thanks guys!

Back in the day when I worked at a Napa store we sold Seafoam by the cases to the local farmers and ranchers and there was no complaints from them, also I use it as a fuel stabilizer and it also helps to clean gum and varnish.

Seafoam and Techron. Both excellent products.

Whether it's a waste or not depends,if you have a chemistry background then yes it's a waste of $$. Depends.

We have an '07 Suburban with a 5.3L that has over 260K miles on it. Motor has never been out of the truck. I religiously use Seafoam in the cranckcase about 200 miles before an oil change. We bought the vehicle used with 212K miles. The engine was plugging the oil pressure sensor filter/screen inside the block (common problem with the LS). I replaced the filter/screen and ran 8oz in the crankcase which is more aggressive than Seafoam recommends. After dumping that oil and running it before every oil change like I stated, we've put over 40K miles on the truck without plugging another filter/screen. Oil gets changed every 5,000 miles using Amsoil OE 5W-30. My .02

Please explain.

Seafoam works great for removing deposits on valves and carbon off pistons. We never pour it in the tank for that..Vacuum line is best but can be dumped down carb/Throttle body at idle feathering the throttle. Let it set for 20 minutes and watch the smoke show and hope no neighbors call the fire department FWIW a mixture of water and trans fluid will also do a really good job cleaning out carbon in the chamber.

i use it in my diesel ram every time i change the fuel filter, i would fill the fuel filter can with seafoam run the truck for 10 mins shut it off for 1/2 hour or longer then take it for a blast down the highway! keeps the injectors clean and the rest of system, i also use the power service product every time i put fuel in the truck!!!! i use the seafoam in my duster once in a while and when i put it away for the winter. i use it all the time in the lawn mower/snowblowers...i would recomend this to use!!!

W/r/t added through a vacuum line:
Similar results reported for
1. Coca Cola
2. Marvel Mystery Oil
3. tap water

I know that for personal amusement , it can't be beat.
A friend back in the day filled the windshield washer reservoir with it , and ran the line to a 90 degree spark plug boot located just above the carburetor in a '71 Ford LTD..........351 W.
He would drive up the street in front of my parents house and be pressing the windshield washer button like it was a coin return on a candy machine.
We are talking James Bond quality smoke screens.
You could not see the house across the street.
It was great.
He worked it hard for about two weeks , until he thinned the oil to the point of catastrophic engine failure.
But we had more than a couple laughs with that one , and when a running , driving car could be had for a hundred dollars , it was affordable fun as well.

I was an Evinrude outboard motor dealer for many years and I was asked this question many times and heard it asked at service seminars nearly every session. Their answer was always the same; for those that believe that diluting any fuel system 'cleaner' so much when mixed with fuel does any good, just take a sample of that mix and put a dirty spark plug or something similar in it for a while. You'll find that it is far too diluted to have any impact.

What they always recommended and what I use to this day is the concentrated de-carbonate products. Sea Foam might even be a version of it. GM has them as well as all the outboard manufacturers. JC Whitney had a version that they called 'Tune Up In A Can'. And it really works well in concentrate. But even it will not be effective when diluted with gallons of gas or fuel. It is all I have ever used to clean carburetors. It is very effective, non acidic, water soluble, and won't hurt the aluminum, unlike carb cleaner. There is a lot more to this subject, but that is the gist of it.

This is still what I use to clean carbs and anything with carbon deposits. There are other brands of the same product, too. This stuff has been around for decades.

https://www.amazon.com/Johnson-Evinrude-OMC-Engine-777185/dp/B001KYJAL0

On the Seafoam, yes I know it works for cleaning injectors. Back in 04, I was driving a fuel injected 89 f150 that developed an intermittent miss. This went on for about 10,000 miles while I checked or replaced most of the ignition system components. It got worse and more consistent with time. So I started dumping sea foam in the tank at each fill. After 3 tanks, the miss was completely gone. I don't know how that can be snake oil?

On the Lucas, I sure will vouch for the transmission conditioner! One of our roofing trucks, an 89 Chev one ton SRW with a 350 that had about 200,000 miles on it was being used (abused?) one day by an employee, who was trying to make it back to the shop with a big load in the bed, and a big overloaded trailer, going into a 30 mph headwind. He walked the last 2 miles to shop and said the truck wouldn't go no more. When I got there, I could smell the burnt up tranny from 30 feet away. The motor ran, but the trans slipped so bad, it would barely move. We towed it back, and I drained and flushed the fluid/filter. Still had major slippage. Dumped in the Lucas, and it somehow, miraculously cured it. We used that truck for at least another few months before I sold it, and it never slipped again. I don't know how that can be snake oil?

On the J.C. Whitney Instant Engine Overhaul: back in 77, I had a 67 Cougar GT with a 390 that burned about a quart every 100 miles. Being young and full of hope and optimism, I spent $6.95 on the Instant Overhaul. Afterall, it had a 100% money back guarantee. The instructions said to dump the honey-like liquid into the crankcase, then bring the engine up to full operating temperature. Then while the engine was still hot, remove the spark plugs, put the overhaul pellets (like Jacks magic beanstalk beans) into the cylinders, replace the spark plugs, and start the engine to repair and coat the cylinder walls and rings with liquid molybdenum.
Well, if you've ever tried to to remove the spark plugs on a big bock, shock tower Ford, you can guess what happened. The motor was stone cold by the time I got all the plugs back in and started it, so the molybdenum didn't have a chance to coat the cylinders. I'm sure if I had been doing this in a 426 Hemi, it would have worked! I don't know how that can be snake oil?

seafoam definitely works. it will clean the carbon up. I prefer gumout mostly because it's a little gentler to use. put a couple of bottles of seafoam in a full tank of gas and it's like giving the combustion chambers an enema. it will really blackens plugs on heavily carboned chambers but will clean valve seats up.

Wonder what that does to catalytic converters?