Changing The Oil: The Deisel Fuel Trick

[Davalos]

Back in the days of my old straight-6 Ford, I used to do what one of the old-timers told me:

 

He said, (and you have to use that old-man-on-the-front-porch-with-a-beer-accent), "Davalos, if you wanna keep that motor runnin, do you this: Next time you change that oil, you drain out the old stuff, and then put yourself a gallon of deisel fuel in there. Yep, Deisel Fuel - listen to me, Kid, I'm tellin' ya. Then you run that motor for about a minute with that diesel fuel in there, no more. Then drain your motor again, pull your distributor cap, and crannk that baby for about 15 seconds. Your oil catch pan will be filled with stuff you've never seen before come outta that motor. Then you change that FL1-A, fill'er up with your 10w40, pop the distributor cap back on, and you're good to go!"

 

Well, after a lot of laughing behind his back, I realized he'd never steered me wrong & had gotten me out of a lot of punches with my old Ford. So I finally got up the courage to do it. Just like he said: drained it out, poured the deisel in there, ran him for about a minute, changed it all back. When I went to check the dipstick level, I was absolutely amazed! At first I almost thought I hadn't added enough oil, because I didn't see any on the stick when I checked after putting in 5 quarts. Turns-out, the oil was clear as glass. After that, that motor ran like a top, and I mean smoooooothe as honey. No lifter noise, no ticking, no nuthin. Wow! The amount of sludge and junk that came out of that motor was inredible - about 5 qts of material came out of the motor, and I had only put-in a gallon of deisel.

 

Now: we're talking a 1986 Ford here, and the 300-6's were notoriously impossible to kill. Once, when my lifters were so bad on my Van, I actually took a 1/2 gallon of WD-40 and poured it in there with the oil - and I drove the thing around, fulling expecting to kill the motor (this was another one of Charlie's tricks). I was surprised beyond belief when the lifters stopped making noise, from TAKKATAKKATAKKA to nothing - we're talking about 30 minutes of driving here, plus another 10 minutes to get me back to the garage. I drained it, filled-it, and the van ran like a champ until it finally rusted-out so bad i was dying from Monoxide Poisoning. The guy who bought it from me still uses it on his farm, and it's still running, 6 years later.

 

Anyone know this "trick" and would they dare try this on a Subaru 1.8? Since then I've heard various things like "you're crazy," "you just put 10,000 miles of wear on that thing," and "You prolly messed-up all dem seals" (you gotta put that thick hick-accent on those quotes). We're talking high-mileage vehicles (the van had 180k+ when I did it, and my truck had 225k on it - Subaru has 160k).

 

After all I've een thru and all I've read on these boards, I'm kinda tempted to go ahead & do it on my Soobie.

 

Whatadyall think?

[SuBrat84]

I do see the logic behind it. Diesel being kinda oily as it is.. It would definately clean out a lot of built up sludge going on in there. However, I WOULD be worried about the diesel fuel accelerating the wear (deteriorating) of any rubber parts and/or gaskets that it comes in contact with. It seems to me like a couple of our gaskets are cork / cardboard? and sometimes kind of weak. If the stuff that holds our motors together wouldn't get ruined I, for one, would use diesel at a rare oil change.

[scrap487]

yeah, usually what I do is just put about a quart or so of diesel or kerosene in with some oil and run it for bout 5 minutes or so... tho I think there is quite a differance between a ford 300 straight 6 and a little subaru 1.8, but I dunno... I'd be tempted to try it on my beast that already has bad rod knock but not on my daily driver.

[azsubaru]

I learned basically the same trick, except we used Varsol - a cleaning agent similar to Kerosene but less flammable; I think it's still available.

 

The method I was taught was to drain the oil, fill it up with Varsol, idle for 5 minutes, drain and fill with fresh oil. It would clean out all the gunk inside the engine. I particularly remember getting hydraulic valves in my 63 Ford to quit tickling. I suspect there were some negatives from it, but I never experienced any problems.

 

Using Seafoam or MMO in the oil to cure the TOD seems to be a less drastic way to do the same thing.

[DualCarb'84]

I have done a similar process with my ea81 when switching from standard to synthetic oils. Amsoil makes a product called "Engine Flush", and seemed to be a solvent based liquid that is added to existing conventional oil. You dump in a quart, run your engine for fifteen minutes, then drain. After removing my drain plug, i had to poke the log jam of sludge that came through my drain hole twice to get my used oil to flow out. I was absolutely amazed at the amount of stuff that was inside my motor. I have about 25k on it since the treatment, and plan to do it every 35k or so. Highly recommended!

[Roundeye]

I've been told similar, but use ATF in place of diesel. Never tried it though. Consequences are too great:dead:

[idosubaru]

i've used about %50 ATF with no ill effect. i don't usually have to do that, haven't for awhile and really never do unless i acquire something already poorly maintained with valve train noise that won't die. try 1 quart ATF, then 2, then 3....then decide if it's really worth trying to go any further. i woudln't unless there was a real reason...like a noisey HLA that won't shut up. couple quarts of ATF might be better than pulling cams and HLA's.

[soobscript]

I have used Seafoam and MMO in the oil, but didn't see anything special drain out.

I also ran straight ATF for about 15 mins at idle for a flush. Then fresh thinner-than-normal oil and filter for 100 miles, then another oil and filter change.

None of that was on soobs.

 

When I had my EA82T apart with 220K miles, I manually scraped varnish chunks and cleaned everything with solvent.

 

I would try pure diesel for a minute. If that sounds scary, you could try a lower concentration first and see what happens.

[4x4_Welder]

It would work, but I'd be mroe worried about plugging the oil pickup while doing it or later on down the road. The pickup screen on these engines is tiny, it wouldn't take much sludge to plug it.

My trick is to do oil changes once the oil starts to get dark, and run Castrol, since that stuff cleans the best.

[Davalos]

It would work, but I'd be mroe worried about plugging the oil pickup while doing it or later on down the road. The pickup screen on these engines is tiny, it wouldn't take much sludge to plug it.

My trick is to do oil changes once the oil starts to get dark, and run Castrol, since that stuff cleans the best.

 

Pickup Screen, eh? Is that the thing you see when you have the oil pan off? Can it be cleaned?

[SuBrat84]

I think that the diesel would probably break everything up enough to get it through the screen. That's the point right? To get the build up out of where it shouldn't be?

[4x4_Welder]

The other concern is that coked oil is really hard, practically pure carbon, and since the oil pump gets the oil before the filter, it might damage that as well.

You can pull the pickup and clean it, I like to let the soak overnight in the solvent tank, then stick the solvent hose down the tube, and let it run for a couple hours to make sure everything is out. Of course, you have to either have the engine out, or jack it up enough to get the pan off to pull the pickup out.

[gunslinger]

the diesel trick works great. ive done it to two toyotas before i did it to both my first subarus. the first toyota i did this to had 297K on it and i had to pull the pan after the 2nd round of treatment because so much crap came down, it wouldnt come through the drain hole!! after i pulled the pan and scraped it all out, i filled up a pop can with the top cut off with all the crap that came out!!

 

you dont fill up with diesel though. in a 4 - 5 quart system such as a subie, you do this mixture:

 

- 1 quart oil, not synthetic

- 2 quarts diesel

- 1 quart ATF

- top off whats left with oil

 

diesel is a cleaner that will do the most work breaking down all the gunk. the ATF is considered a "conditioner". dont worry about the diesel breaking down any rubber parts in the engine. because (1) as far as i know, there isnt any rubber where the oil gets to and (2) the diesel isnt in there long enough to do any damage.

 

start it up and idle it for about 10 to 15 minutes. drain your oil and check out all the crap that comes out. sometimes you WILL have to poke a hole in it to get it out - especially since most of us have rigs that have 170K + on them and they arent exactly driven in the most desirable curcumstances. repeat process as many times as you think it takes till the mixture looks semi clean. fill the engine back up with oil. i recommend synthetic. synthetic oils FAR outperform their natural counterparts.

 

dont worry about the oil pickup. the diesel does a pretty good job of breaking down the deposits.

 

all this comes from my own experience of doing this and initially came from a good friend of mine that owned a small oil additive company and is a mechanical engineer.

 

i would recomend this trick to anyone that would like to keep the internals of their motor clean. ive done it and it works great!

 

:)

[Uberoo]

ok so then one Quart diesel,one quart atf and the rest oil....might have to try that once I get the motor back together.that being said after I pulled ahead I was amazed at the disgusting mess in there.