Pick this procedure apart..
old timer taught me this one for cleaning out carbon deposits. Wondering if you think it does anything? Or works?
Basically, take the plugs out and pour a few oz of marvel mystery oil directly into each cylinder... With the plugs out, cycle the engine just a bit and spread the oil around and into the valves.. Then let it sit overnight.. Repeat.. Then cycle it alot to throw most of the oil out of cylinder.. Reassemble and fire it up. Seems to work - I have done it a couple times, but who knows..

 

You don't really need to spend the money on MMO. Diesel fuel is the same stuff, and an even older old school.

 

Back in my mechanic days we would use a cup of water to clean up carbon deposits. About 2500 rpms and little by little pour the water straight down the carburetor. Never killed an engine but it was risky.
Man, I feel old.

 

The last time I had to clean out carbon deposits was .......... Never.

 

I think deposits on modern engines are insignificant, and would need to be VERY thick to create any sort of problem.

 

I was burning some oil and suspected a stuck oil control ring. I was the lucky one and a SeaFoam treatment did burn the carbon off of it.

Almost all of the "Miracle in a can" stuff is "jet fuel" otherwise known as kerosene/diesel fuel.

 

Can't beat tear it down clean it put it back together with new valve guide seals and gaskets!