Pouring Diesel Fuel In/Through Crankcase to Clean

[HangerHarley]

At OC, when Oil is drained, before new fill..

1) What is the right way to do this

2) Why do some people do this

3) Wont the car smoke a little after you do this

4) On any car 10 to 15 years or older, would you do this?

5) Can it hurt?

 

[Johnny]

Absolutely DO NOT do this and who ever said it is okay is a fool.

 

[ryan2022]

hmm, never heard about Deisel fuel, some other may be able to chime in. I'd lean towards Sea foam or even ATF.

Id be interested in hearing though.

 

[The motor guy]

Diesel fuel in the oil is like a number one or number two killer of an engine. I think glycol is number one.

 

[bigmike]

My dad told me about a guy that used kerosene.

No reason to ever do something like this IMO.

 

[SuperDave456]

Ive heard of people using an extra quart of oil to "wash out" old oil in the engine.

However, they are very misguided. There is a lot of oil in the engine that is left behind, and little of it is in the drain pan.

I have also seen people drain their pan, put the plug back in, then put a can of Berrymans B-12 in their crankcase and let it sit in there for 20+ minutes without starting the engine. Supposedly this "loosened up junk in the pan" and allowed it to drain out.

I wouldn't do either of the above, nor would I use Diesel fuel.

I would say that you have better options if you need to clean up an engine.
1. Shorten your OCI.
2. If you really feel like it add a pint of MMO your last 500 miles of your OCI.
3. If you feel really daring add a full quart of MMO to the last 500 miles of your OCI.

Your mileage may vary. But if you have a sludged engine you would be better off with several short, 3,000-4,000 mile, OCI's than using any chemicals at first. Letting the cleaners and detergents that are in the oils do their thing first before you decide to use some harsh solvent that may clog your engine with the stuff you are attempting to get out.

I don't see diesel fuel having any characteristics you would want for a fluid you would want in your crank case.
But I have heard stranger things.
I wouldn't do it.

 

[OpelFever]

From what I've heard, using diesel to clean an engine is an old farmers trick. They add an unspecified amount of diesel to the oil at OC and let it run for 10-30 minutes, just like your regular engine flush.

Supposedly the engine won't be harmed since Diesel-"oil" has some lubricating properties and the car is not driven while the diesel is in the crankcase.

I'll experiment on this some day when I find a suitable beater, but I don't recommend doing on a decent car due to obvious risks.

BTW diesel has very good cleaning properties as can be witnessed when a leak occurs: it removes any protective anti-rust coating on the chassis and a lot of dirt.

 

[The motor guy]

If you change the oil on a regular basis. Say every 5000 or so then the inside of your engine should be spotless. No need to do any type of decarboning or anything like that.

 

[edhackett]

The owner's manual for my 1941 John Deere calls for the engine and transmission to be flushed with a fill of kerosene yearly. The technique was used to remove sludge due to the use of non detergent oils.

Absolutely not necessary or recommended with today's oils.

Ed

 

[tinmanSC]

Best avoided, IMO.

 

[BMWTurboDzl]

IIRC most 'engine flushes' (MMO included) are very similar to or contain kerosene/diesel. Typical application was to drain ~1 quart of oil and replace it with the same amount in diesel then run the engine at idle for ~ 10 minutes after which you would drain and refill with clean oil.

Diesel/Kerosene is a solvent and the idea is that it would help remove/dissolve sludge.

 

[Ken2]

Diesel is a poor solvent. Kerosene is much better...and I've scrubbed plenty of parts in both. The engine flush products are different. They are much more volatile and will rapidly boil off any remaining in the engine with a little heat.

A big problem with a diesel or kerosene flush is that you'll never get all of it out of the engine until you refill with oil and drain again. It won't just drain completely out. And, it won't do any good. The volatile solvent flush products do little good as well. Their main virtue, and a small virtue at that, is that they thin the oil so more drains out when you change the type of oil. This is not a big deal. Save your money.

 

[mechtech2]

Old tips and techniques like this have no validity in today's world. Even back then, they were more than questionable.

 

[HangerHarley]

Originally Posted By: mechtech2
Old tips and techniques like this have no validity in today's world. Even back then, they were more than questionable.


See, thats my "Idiot mechanic's" advice again.

Im debating puting ANY MMO in the crankcase. Seems like it is not needed. As i get ready to go back to my car, next year...

Simple test: if i run the car with the expansion cap off, what type of behavior should i look to observe, to verify i dont have a problem with the engine?

FTR, Im interested in checking that myself.. since IF a Head Gasket was needed, it would be RTV Silicone/Gasket Maker, etc etc..................... on top of a gasket, if a gasket was used, ...................... I also think its OK, though at this point, id like to check, and id be going back to a car that sat for 9 months to a year, newly installed Water Pump. My oil always looked nasty upon drain, hopefully that will stop soon. That too seemed "inconclusive." This is from memory.

Just saying.

 

[ahoier]

Never heard of Diesel in the crankcase....but I can vouch for both MMO and Seafoam in the crankcase at the recommended amounts.

Note: next have used MMO as a "fast flush" as most will document, I've only used it per the bottle directions, replacing 1 qt of my 5 qts of oil, with MMO....so basically, for a 5 qt crankcase, 4 qts of motor oil (PYB, if you will) and 1 qt of MMO..

With my latest find, the 88 dodge aries, that's been sitting most of it's life (only 29k or so on the clock....) I took the plunge, when I picked it up, I noticed the dipstick was showing low on oil, so I added 1 PINT of MMO to the case to bring it to full, then took it for a spirited drive to a friends garage were I dumped the oil out (wow, was it dirty....lol, it even still had it's "Mopar" Next oil service sticker in the windshield, and it wasn't "due" yet for service...but like I said, it's been SITTING in the Florida heat for a long time) and let it drain good (gave it 15 minutes or so), popped the drain plug back in, added 1 PINT of MMO, and 3 and a half quarts of PYB...since the bottle states to use 20%, this 4 qt sump only needed 1/2 qt of MMO (so I opted for the 1 pint bottle for ease of use).

I'm now 1000 or so miles into that OCI and my dipstick is still it's golden color....

But when I drained that initial MMO+oil out, that oil had a dark black color to it Definitely could see the oil on the dipstick..



On my other cars, 07 Kia Rio and 08 Kia Optima, I used the 1.5 oz per qt of Oil in the crankcase every OCI....and no problems. They were previous "rental"/lease cars, so "should" have been kept up on maintenance but immediately after each purchase I always used one dose of Seafoam in the crankcase and that first OCI was always nasty


Bottom line, a flush here and there won't hurt I don't think, but flushing EVERY oil change likely isn't necessary....just use quality oil (API/GF/donut-rated Oil lol).


To this date though, black soot still is pouring out of the tail pipe on start-up of that 88 aries.....it's got some nasty build up somewhere in there, cause it's leaving black "soot" on my drive way....lol.

 

[Jakegday]

Originally Posted By: bigmike
My dad told me about a guy that used kerosene.

No reason to ever do something like this IMO.


the owners manual to my fairmont recommends something like 10% kerosene in your oil in extremely cold weather.
that was 1981, however.

 

[pidster]

Originally Posted By: Jakegday
Originally Posted By: bigmike
My dad told me about a guy that used kerosene.

No reason to ever do something like this IMO.


the owners manual to my fairmont recommends something like 10% kerosene in your oil in extremely cold weather.
that was 1981, however.


That was intended in older vehicles as a manner of quickly thinning the oil for an arctic cold start, not for cleaning. Thought that concept was gone from manuals waaay before 1981? I guess not.

 

[beast3300]

Just change your engine oil at a reasonable OCI and your engine will be clean. And if it's dirty, it will clean up in time.

 

[Mark R.]

Like others have stated, if a normal OCI is used this would be a non issue. That said, an old backyard flush was add a half gallon of diesel, start engine and allow to idle for 20 or so minutes. Then change oil & filter as normal. Stuff that ran out was black and thin...

 

[M56959]

If a topic interests you please start a one.

Responding to a decade old topic helps no one.