i think its about time for an engine flush

i changed my oil about 20 miles ago and allready its black again i took off the oil filler cap and all i could see was sludge

any suggestions about a good solvent to flush out my motor i've heard Marvel Mystery oil is good, Gunk 5 Minute Motor Flush is good, 4 gallons of kerosene? i know kerosene is some powerful shtuff and a good cleaning agent but what? i heard dump it in disconnect both wireing harnesses from the distributor and crank it don't let it start tho

i'm looking for some thing i can do myself and not destroy my engine in the process

any advice would be a major help

i changed my oil about 20 miles ago and allready its black again i took off the oil filler cap and all i could see was sludge

any suggestions about a good solvent to flush out my motor i've heard Marvel Mystery oil is good, Gunk 5 Minute Motor Flush is good, 4 gallons of kerosene? i know kerosene is some powerful shtuff and a good cleaning agent but what? i heard dump it in disconnect both wireing harnesses from the distributor and crank it don't let it start tho

i'm looking for some thing i can do myself and not destroy my engine in the process

any advice would be a major help

black oil means carbon....you may have a poorly running ignition system....or the carb is set improperly, also too rich a mixture...and other componets...MAP....etc... if the plug tips are lt brown all should be good there if black correct the poor combustion problem[s]....


ON flushing out a very gooped engine [sludge] I unfortunately had this experience with a vehicle my son bought...


using Marvel Mystry oil at no more that 8oz a few miles before changing oil when at the operating temp is the safest.....


Use of the other products as you mentioned the kerosene at 1 quart /crankcase is the most I would do...

If you use the kerosene. I run engine for 15-30 minutes ,do not put in gear...then drain then replace the filter then refill , then run engine for 15-30 minutes then drain and fill .... If you don't do this kerosene will be left in the engine and the goop will not be fully flushed out...remove the filter and dump out the oil re-install or replace depending on what you find in there...


I have done the exterme method several times, and to my surprise this vehicle ran another 80,000mi before being sold .....

the engine did not suffer any after effects no leaks and no change in oil consumption...

What oil are you using? Pennzoil and Quaker have had sludging problems from excessive polymer use for a long time. The higher viscosity spans exhibit this tendency even more. A good air filter and functioning PCV system are also necessary to help keep the crankcase clean. IN almost every engine, most of the contamination in the oil is from particulates drawn through the air filter. The particulates which are not soluble and not filtered out will form sludge quickly.

If you see sludge accumulation (more than just a light film), it might be best to remove the rocker covers and clean all you can from inside the covers and around the heads' valve guide and rocker stud bosses, drainbacks, and springs. Don't bother disassembling anything, but clean all that is accessible. That will be a significant amount of sludge that will not be free to clog the oil pump inlet screen and will not be present to contaminate the new oil you use.

As for cleaning processes, kerosene (diesel fuel), automatic transmission oil, and dedicated purpose solvents can help loosen sludge. As previously advised, you would need to run the engine (NOT under any load) long enough to get the engine and oil hot enough to soften sludge, and with enough RPM to produce adequate oil pumping volume and slinging in the crankcase to clean off sludge. Changing the oil filter after one of these episodes is a MUST. You might have to change oil frequently for a while before it no longer releases contamination shortly after changing.

Fully synthetic (PAO) lubricants do a very good job of cleaning sludge formations and softening seals. That may be a worthwhile alternative.

i would not use quaker state if my life depended on it way too much parafin wax at the current in time i'm using Valvoline syn-blends 5W30 i know my car is running rich thanx to a fuel dumping injector the odd part that gets me is that i've known the prescence of blow-by gases to be a whitish smoke seen when you remove the oil filler cap with the engine running my loved lil' 305 does not exibit that sign i know the pcv valve(s) are shot prolly could be cleaned but i'd rather replace them ohh and when i bought the car it ran for about 15,000 miles with out an air filter or oil change i wanted to smack the guy and had to use every bit of self restraint to not do so

so i think i'm going to buy a bottle of Gunk 5 minute motor flush, new oil, oil filter and Prestone Engine Restore i love that stuff i use it religously with every oil chage and use some lucus oil stabilizer too that cock tail in my engine has allways impressed me

Has anyone heard of an engine flush product called Seafoam?
I have read about it in other forums and just recently saw it at my local auto parts store. It is supposed to be the stuff to use for cleaning the internals of your engine.
I have not used it, just wondering if anyone else has.

Al :smokin:

SeaFoam is not an engine flush. As a matter of fact, other than cleaning out carburetors which have already been removed from the engine, there isn't much for which it is actually suitable. Putting it in fuel is not good, (especially in injection systems) since it contains water. Putting it in oil is not good, either, since it contains alcohol and naptha. Metering it through a vacuum hose to the intake to clean combustion chamber deposits might be O.K., but straight water or a water/methanol mixture (such as windshield washer fluid) would be much more effective.

As you can tell, I'm not a big fan of SeaFoam nor the way it is marketed to unsuspecting consumers.

AutoRX, not cheap but safe and effective. Have used it myself andtaken one engine apart repeatedly for cam, heads/cam swaps and it really does clean. Even the gunked on stuff on the underside of the intake manifold.

@ bowtie, Seafoam is a wonderful product if you know how to use it. I have put it in crankcases many times.

If you are sludged up, and need to break it down, seafoam in the crank is the longterm solution. It is what I used when I was afraid of the kerosene. However, it is the same concept. I used it idiling 45 mins-1 hr at a time. Turned engine off after it was good and hot and did it again in a few hours. Drove it no more than a mile here and there to get some fresh gas from the corner store. prolly burnt a 1/4 tank of gas through the process over 2 weeks. When you let it idle, you wont get those chunks of goo clogging up your oil pick up screen. Safer than the kerosene route but takes longer. I have heard of using it long term, but not sure if i would ever do it.

@ bowtie, Seafoam is a wonderful product if you know how to use it. I have put it in crankcases many times.

If you are sludged up, and need to break it down, seafoam in the crank is the longterm solution. It is what I used when I was afraid of the kerosene. However, it is the same concept. I used it idiling 45 mins-1 hr at a time. Turned engine off after it was good and hot and did it again in a few hours. Drove it no more than a mile here and there to get some fresh gas from the corner store. prolly burnt a 1/4 tank of gas through the process over 2 weeks. When you let it idle, you wont get those chunks of goo clogging up your oil pick up screen. Safer than the kerosene route but takes longer. I have heard of using it long term, but not sure if i would ever do it.


If you are in need of using these products as you say, then I suggest you change your oil more often , and use high quality oil filters.

having owned only 4 vehicles since 1967 and with 10 plus yrs on each with well over 100,ooo/300,ooo mi I have never had sludge issues that required these drastic actions.

I have worked on abused engines and I know that once you get into sludge issues the engine is worn out , damaged. low oil pressures at idle when hot ,,, is a sure sign that the owner went to far on changing to oil. or perhaps the quick lube guy did not change the oil ...!

With a good running engine that has a slight amount of engine oil sludge do to a component malfuntion the use of products that gradually remove crankcase deposits. this will allow the high quality oil filter to catch these deposits and over a few thousand miles clean the crankcase with out damage to the oil so that wear is not an issue.

Marvel mystery oil is a well known product that cleans AND LUBRICATES.. used in small amounts of 1 ounce per quart of crankcase capacity which for most engines is 5 oz. will clean and lube the engine safely..

using strong solvents when changing the oil , on a severly sludged engine may require several oil changes and filter replacements to properly clean out the engine so it can function ..this means gallons of oil and a few oil filters at this time of cleaning, to try to get the engine clean enough , so it can work better for a time...until it sludges up again due to the engine wear issues with it.

I've used MMO in the past to cure a sticky lifter in my Vibe and I used it according to the label instructions. They state to use alot more than the 5 oz./crankcase you recommend...20% of the crankcase capacity, which would be 1 qt for the average 5-qt crankcase.

I'm not trying to call you out, just noting the difference between you and the mfr where using too little may not get the full cleaning effect that may be needed in severe cases. But I will agree that reducing it would be prudent for light cleaning.

I've used MMO in the past to cure a sticky lifter in my Vibe and I used it according to the label instructions. They state to use alot more than the 5 oz./crankcase you recommend...20% of the crankcase capacity, which would be 1 qt for the average 5-qt crankcase.

I'm not trying to call you out, just noting the difference between you and the mfr where using too little may not get the full cleaning effect that may be needed in severe cases. But I will agree that reducing it would be prudent for light cleaning.

you are correct that 5 OZ in the crankcase is MY recomendation...of the marvel mystery oil. I have found that is all that is required and that more is not better good or required. the purpose I am looking for is to slowly break down crankcase deposits that can from time to time cause lifters to stick and other noise issues with components carboned up.

I also add to the fuel marvel mystery oil at 1 OZ per 10 gallons of fuel. this to is my recomendation not the manufacturer. this cleans the fuel system ,lubricates the fuel pump/lifters and is excellant top end engine valve/compression ring conditioner..I found this treatment makes the engine run very smooth and a slight MPG increase when used at the higher hyway speeds 70-80 mph...

bottom line here is this product is safe.I have never had any issues with this product ..it does work..

with a fouled sludged engine worn out theres no product that can make it run much better.