Audi Junkie

1991 100 Auto, 140k. I pulled the plugs and cleaned them, gap at .040, close to the worn reading they had upon removal. (what gap is the oem gap?) While the plugs were out, I poured in a Witch's Brew of solvents and light oils. (through a tiny funnel, not just poured sloppy around the holes) Maybe best done when engine is warm and allowed to soak overnight, but I did not have a lot of time, so maybe a 5-10 min soak.
I used BP Blaster, 2-cycle oil, Acetone, Pentosin, MMO, SynPower FI cleaner and some other stuff. About 2-3oz in each cylinder (after vacuuming out the plug area). I crank it w/o plugs to swish the mix around. Let it sit while installing plugs. It soaks into the carbon, not dissloving it but allowing it to break off of the metal surface and be blown out. Easy to see how it frees the ring pack.
It really worked well. Even though I did clean the plugs, they were not too dirty at all. Engine is MUCH smoother and power is...well, it's smoother....a lot smoother. Other methods involve hot engines and water piston soak. Some use water into the intake like SeaFoam.

RB-200 20v

Man, chunks of carbon flying around a combustion chamber doesn't sound like a good thing, then trying to get out an exhaust valve to promptly get stuck in a cat.

Was this procedure and "cocktail" of your own design or is there documentation somewhere?

You did change the oil post treatment?

dwengi

2ND on the oil change

Audi Junkie

23mpg last tank, pretty good considering I was driving in heavy snow and I was stuck twice. Any excess solvent in the oil will be burned away quickly. imo, piston soak is a must-do for an old car. I've seen borescope pics of before and after water treatments, pretty impressive.

RB-200 20v

How can solvents in oil not do harm? While it's "cleaning" it's also washing any lubricant off anything that needs it, if it wasn't it wouldn't be "cleaning". Cylinder walls, crank journals, cams, etc. all without proper lubrication until the solvents "burn-off".

Water may well clean, but it's water, not acetone, the oil will still lubricate.

If you have a catalytic converter what kind of damage will those solvents do to it?

To each their own, but, I see more harm than good coming from this!

Audi Junkie

Ahhh, yep...water is a lubricant. While it's always good to be cautious, the opposite of what you said appears to be true, that MORE good came from it than harm. Light aeromatics in oil is a normal condition, all it does is simply thin the oil for a while until it evaporates. There are formulae for calculating visc drop from fuel dillution, I don't have one handly, but the OA labs flag it at 5%, that's a lot of solvent! That's because it's an on-going fuel situation than need to be corrected. More is coming in than going out. IN my case no more solvent is coming in and it will burn off in a matter of hours. About half of the 12oz I used was solvent, maybe less than half of that can make it into the oil and the resultant visc drop is insignifigant.
I'm trying to address your questions, but doubting everything someone does for the exercise of it is not an enjoyable format for the poster trying to bring new ideas to a stagnant forum. My cat is fine, I got 26 mpg and this otherwise sludgy/carbonized car is running better then it has in 5 years.

RB-200 20v

Come on, if you can't take critique you shouldn't post a questionable process to a public list.

Audi Junkie

I never said I couldn't take criticisim. I said your criticisim was vague and baseless.

Mr. Head

Water Based product...<ul><li><a href="http://www.orisonmarketing.com/cleaners/piston/carbon.html">http://www.orisonmarketing.com/cleaners/piston/carbon.html</a</li></ul>