[78w72]

ATF may be used in some manual trans & xfr cases... but it does not have the properties required for engine lubrication, detergents and neutralizing acids from combustion. Cant comment on the forces on gears doing a clutch dump, but its not the same type of force that requires high levels of anti wear and lubrication of engine oils, maybe those trans are designed to be able to use ATF but I would never use it at full strength in an engine, and from what Ive found with basic research, it doesnt clean as well either.

Not sure if phos is a detergent, it is used mainly for anti wear in combination with zinc to form ZDDP. Detergents are usually calcium, sodium, magnesium etc. Regardless, the PPM numbers are very low and not even close to the levels required for engine oil, phos & zinc are usually in the 900ppm range for off the shelf oils, specialty/race oils that so many people claim are needed for even stock broken in cams have 1000-1500 PPM zinc/phos, Dex3 ATF is 159phos & 17zinc!

Hey, looks like there is 1 vote for pure ATF now... was that mr mike or another member? Please, post a comment as to why you voted for or use pure ATF in your engine.

[59safaricat]

I've seen all of these work and more on friends/family vehicles. Seen MMO/Seafoam/1qt ATF unstick noisy sticky hyd lifters, sometimes within a couple minutes. Seen 15/40 diesel oil clean things up after a few oil changes using it with surprising results by pulling the valve covers for before/after shots. Heard of people using various amounts of kerosene/diesel fuel but never tried it myself. Me, I've always done all of my maintenance according to the severe maintenance schedule so I never had to use them in the crankcase of my personal vehicles but I had fun experimenting on others.

[TedRamAirII]

I cant see putting a quart in and just driving it, will hurt. Sludge needs to be dissolved gradually, just like it formed. I would use MMO and drive it 1K and do a oil change, then do it again. Cut the oil filter open and see what's going on. Not sure what to look at to measure progress. Peek at the oil filler hole in the valve cover?

[78w72]

Originally Posted by TedRamAirII

I cant see putting a quart in and just driving it, will hurt. Sludge needs to be dissolved gradually, just like it formed. I would use MMO and drive it 1K and do a oil change, then do it again. Cut the oil filter open and see what's going on. Not sure what to look at to measure progress. Peek at the oil filler hole in the valve cover?

Agree 1qt of ATF or diesel etc shouldnt hurt the engine but taking it easy while driving a short distance or idling since it does dilute the oils properties is a good idea... but the main point is ATF has much lower amounts of detergents as normal oils, so there isnt any reason or advantage to using it at any concentration over normal oil or other products designed to flush/clean an engine.

With the analysis results showing how low the detergents & all other additives are compared to oil, I hope this shows that using ATF to clean an engine is a flawed myth and using it full strength in an engine is not "wise" and will cause excessive wear that is just asking for problems.

Thanks to those who have voted so far.

[TedRamAirII]

Yes, ATF doesn't have much detergent. Trans stay clean, because the oil stays clean, no combustion by products. That's why I think MMO is the way to go.

[ANDYA]

Filling an entire crankcase with ATF or kerosene is a little extreme and will probably do more harm than good. I am a believer in Marvel Mystery Oil and have seen it work as claimed many times over. I’ve used it many times in the past to quiet a noisy lifter or to clean out a high mileage engine but within reason. Trying to clean out an engine caked up heavily with sludge is looking for a miracle. I have noticed if I add a bottle of MMO to my oil a hundred miles before an oil change that the oil comes out very black so it is cleaning something out.

A neighbor of mine was the original owner of a 1970 Nova. Just a 350 2 barrel that was his daily driver up until he passed away in 2005. He managed to put over 230k miles on that car. As he got older I would help him work on the car, tune ups, oil changes etc. One time as we were changing the valve cover gaskets I remarked that his heads were amazingly clean for such high mileage, almost spotless. He told me that he had been using MMO in every other oil change since the car was new. I have seen many high mileage well maintained engines in my life that got oil changes at regular intervals but never one as clean as this.

As for the engines in my classic Pontiacs I never add anything but high quality, high zddp oil. I put very little miles on each one and I change the oil every year.

[glenn911]

in '88 i had a '76 plymouth fury i bought off original owner. At 100k I wanted to clean up engine so removed valve covers to paint them. There was an 1.5" or so of hardened sludge in them! I used a putty knife and scraped them clean. My Dad said to fill it with kerosene run it and drain it. I did, and a lot of stuff came out. That engine ran for several years until the trans went out, but man, did it smoke when you got on it after that flush!

[Tim Corcoran]

When I was in the Airforce back in 1973 I had a nice 67 GTO with an HO engine, PS, PB, AC, TH-400, his her shifter, a very nice car. I put in a quart of engine flush and followed the instructions. Drained it and put in fresh oil and filter. Right after that I spun a rod bearing, I don't think it was a coincidence. I would never use any engine cleaner after that, commercial product or home brew. After that I picked up a 455 short block from a wrecking yard installed it with all the factory 400 stuff and it ran great and hauled ass and all was well.

[1968GTO421]

My take away from all the replies is to do frequent oil changes with a quality oil/filter and that should make a dirty engine come clean. Even if not a dirty engine to start with, just doing regular oil/filter changes will keep the engine clean inside. Lots of good info in this thread.

[hurryinhoosier62]

I’m not really a fan of “flushing” engines, period. Using MMO to free stuck rings and noisy lifters, yes. I’ve seen this work, but most of the cases of flushing engines I’ve seen ended up with other oil related problems in the end. Just put my Silverado back on the road after having to let it sit for three years( couldn’t depress the clutch with a blown out knee). Simple process: drain out the old oil ( full synthetic 10W30), replace with 10W40 synthetic blend with one quart of MMO. Run for 1,500 miles; replace the leaking timing cover ( typical for GM 4.3 V6s in truck applications ), drain and replace the 10W40 synthetic blend with 10W30 fully synthetic.

[RocktimusPryme]

Arent there some lifters or rocker brands that say you should soak a roller rocker for instance in ATF for a while to clean it before install? I feel like Ive read that somewhere.

Of the list ATF, or a commercial product make the most sense to me. However, that is a realative thing. Im much more in the camp of, "just use good oil"

A diesel flush to prevent corrosion makes sense, though I think I would have stopped at a flush without running it.

My thoughts on this are that we are well into the information age. At this point, most things hot rod-related that really honest-to-goodness work are well documented, and tested. We arent in the, "My nova with a 3/4 race cam jumped Coke cans in the rain" anymore. The very fact that we are debating it, makes my Spidey Sense tingle about the subject.

[tom s]

When a marine engine sinks in SW,they raise them,drain them and what they call “pickle”them by filling with dsl.Then they go through the routine of getting them running again.FWIW,Tom

[Lemans64]

My Uncle who was a long term heavy duty Mech was a firm believer in putting a quart of ATF in the diesel fuel system as well as engine oil.
Said he very rarely had any injector issues or engine oil sludge issue, internals were clean somewhat. ATF was supposed to have high detergent properties.

[VCho455]

I wish the PO of the 64 Galaxy I bought back in 82 would have flushed the 352 with something, at some point.

It was an ex-police car so it probably had good maintenance in its early years. By the time I bought it it was very tired. I paid $200 and negotiated for a full tank of gas. Then I drove it for several weeks before I pulled the engine, transmission, and rear axle and installed them in a 52 F-1. I rebuilt the engine before installing it in the truck.

When I pulled the valve covers there was an almost perfect casting of sludge under the inside of the valve covers. The sludge in the top end was inches thick in places, and not one of the rocker arms was visible. Each valve operated in a small hollowed area that allowed the oil to drain to the valley.

The lifter valley looked like the badlands of South Dakota. The oil pan was so full I would be surprised if it held more than 3 quarts. I rebuilt that poor old FE after spending a week cleaning parts. It was a good runner afterwards but, oh man, what a mess!

[TedRamAirII]

Originally Posted by Lemans64

My Uncle who was a long term heavy duty Mech was a firm believer in putting a quart of ATF in the diesel fuel system as well as engine oil.
Said he very rarely had any injector issues or engine oil sludge issue, internals were clean somewhat. ATF was supposed to have high detergent properties.

ATF has less detergent than cheap motor oil. I don't think it hurts in a Diesel Fuel system,

[Tim Corcoran]

Engine flush is like chemo therapy. It might do some good but the side effects will kill you. Break that crude loose and clog up the oil pickup or spin a bearing etc... If I hade an engine that was full of crud I would either just run it as is or take it all apart clean everything do a light ball hone put in new rings and bearing and put her back in service.

[Sirrotica]

In a diesel fuel system you're trying to dissolve varnish on stuck poppet valves, ATF will definitely dissolves varnish. In a transmission that has been neglected, and a transmission tune up will dissolve the varnish, and usually stick the hydraulic valves in the valve body pretty quickly after a fluid and filter change.

Varnish and sludge are different, so the ATF will dissolve varnish, but won't do much to dissove sludge. I believe the ATF idea was based on using ATF to remove varnish from hydraulic lifters when they stick. Being a hydraulic oil it will sometimes quiet hydraulic lifters, if the noise is caused by varnish. It doesn't work 100% of the time, I've seen it succeed sometimes, but other times it doesn't do anything, it depends what the problem is.

Cleaning up sludge in any neglected engine is rolling the dice. I've seen many that have tried to clean them up in different ways. Honestly in what I've seen a bunch that have tried lots of different methods of cleaning. From what I've seen your chances of success are about 50/50 in a really coked up engine. No matter what happens, even if the engine doesn't starve for oil, and spin a bearing, the neglect has shortened the lifespan of the engine measureably.

If you wqnt to devise a plan to clean one you first have to know what sludge is comprised of. Sludge is the accumulation of all the small particulate that passes thrugh a conventional oli filter. It forms chains and attaches to like particulate, then settles in portions of the engine that have slow oil flow. When the fine particulate can pass through a conventional filter gets to a saturation point that overcomes the overworked detergent package, it drops out of suspension, and accumulates in pools, then it attracts more fine particulate and the deposit grows larger.

I have never done it, but have read that a by pass filter with fresh clean oil will slowly start to break up the sludge, the small particulate will be caught by the by pass filter and slowly remove the sludge. I prefer the slow little bit at a time method.

Pontiacs are very suseptable to a luge amount of sludge being disturbed all at once, and sucking it into the fine screen in the pickup. I have tried to salvage half a dozen badly coked up Pontiacs over the years, none ended well.

Buicks have a small trap door on their oil pickup tubes that will open even if the screen is plugged, too bad Pontiac engineers didn't use that design too.

If I ever run into another sludged up engine I'd like to try the by pass filter with fresh oil method............YMMV

Links to Project Farm, comparng ATF, to Seafoam, to clean an engine: https://www.youtube.com/watch?v=wT0T...el=ProjectFarm

Using ATF as engine oil: https://www.youtube.com/watch?v=bE2F...el=ProjectFarm

[MatthewKlein]

Originally Posted by 78w72

It was requested by another member to do a poll in a recent off the rails thread to see what others think about doing this, it was stated a few times that his engine is cleaner than anyone else on here because it was filled with 2 gallons of pure ATF and ran for 30 minutes... 2 different times.

I mentioned a few points on why doing that was not a good idea for the engine and even posted a link to a reputable oil company explaining some reasons, but was met with an "opinionated argument" as to why that is all nonsense because a “wise” mechanic told him to do it. Keep in mind, the old DIY way of doing this was to add about 1 qt of ATF to the existing oil and run it for a short time before an oil change, just like any other engine flush product, NOT filling the engine with 100% ATF and running it for half an hour.

Most members on here know a lot about engine oils and their additives, that ATF does not have, to protect against wear & extreme pressures such as cam/lifter wear as well as detergent additives that are much stronger than ATF since ATF isnt designed for internal combustion uses, its hydraulic fluid. There is no zinc/phos (zddp) in ATF and with all the fuss about cam/lifter protection, I was surprised nobody commented on that when it was mentioned, bet the cam and lifters loved pure ATF!

The poll is to vote for using 100% ATF in an engine. 1 qt of ATF diluted in the oil. Using a real engine flush intended for that purpose or products like MMO or seafoam etc & following the simple instruction on the can. or, just using a good oil and changing it as needed? Feel free to add any comments on the reasons using pure ATF is a good or bad idea.

I have used BG109 engine performance restoration for over 20 years. BG products are the only engine/transmission/coolant/power steering flushes I have personal experience with. They work well.

When we still regularly serviced engines from the 80's and earlier it was not uncommon for them to be so full of sludge the lifters were covered and under the valve covers was also full. We never really did anything about it and the engines didn't seem to mind.

In the early 2000's I swapped a used 440 into my Charger from a New Yorker. During the cam and intake swap I was saddened to find the engine full of sludge. That engine ran before and was my only option so in it went. It burned 1qt oil in about 1000 miles. Over the next few years I ran the car 500-1000 miles a year changing the oil annually. In 2003 I drove the Charger from Illinois to Las Vegas. Stopping overnight in Denver at a friends house. Sure enough it was down 1qt oil. Over the course of the 3600 mile trip I continued checking the oil but the consumption had stopped. The engine had fresh oil before the trip and with the steady hours of highway time the stuck rings had freed up. A few years after that I changed the intake from an Edelbrock RPM to an old DP4B. With the intake off I was surprised to find all the sludge gone. 5 or 6 years of 500-1000 mile oil changes had allowed the detergent oil to clean the engine spotless. That engine is still in the car now with over 25,000 miles since the swap.

My father graduated in 1969 and has been in the auto repair industry his entire life. I went to work for him in 1996. If a customer had cranked an engine in the winter excessively that wouldn't start he was always quick to check the oil for fuel contamination. If contaminated the oil was changed immediately before anything else. Dad would relate several experiences from his younger days where engines had thrown rod bearings just idling to warm the fuel contaminated oil for replacement. Because of this he was very wary of engine flushes as they are usually very thin. When the BG salesman first tried to get us on board it took some convincing. The first vehicle we tried was an old 3.8L Buick of mine. It had a bad misfire because one cylinder only had 90psi compression. Short story is the flush raised compression in all the cylinders and specifically the 90psi to 110psi. The misfire went away. After that success we flushed my brothers 72 318 with a compression test before and after. Some cylinders improved more than others but they all improved.

Modern engines have extremely thin low tension rings. We see a TON of GM Dexos vehicles burning oil. That BG109 flush will always improve the consumption and sometimes eventually eliminate it. I always recommend to all of my customers to go back to 3000 mile oil changes with 5000 being the limit only if they have a large commute .
BG also offers other induction flushes for the GDI vehicles that develop misfires from deposits.
Before I forget - BG109 does not remove/disturb sludge. It cleans rings and hydraulic valving.

So of the engine flushes I've tried they work. I also believe in detergent oil with a 3000 mile interval.

My 2c

[Tim Corcoran]

I had a TH-400 built for my drag car a few years back and the guy told me to put in a 50/50 mixture of Dextron VI (synthetic) trans fluid and Mobile one engine oil, can't remember the viscosity of the Mobil One he recommended. And I ran what he said and never had any problems with the trans until I broke the bell housing off on launch. I since have cut off what was left of the bell housing and installed a super bell. Still running it.

[TRADERMIKE 2012]

Originally Posted by i82much

I did a very thorough engine flush on an old 396 once. I flooded the engine with about a gallon of raw fuel and went for a 30-minute drive ... finally noticed a strong fuel smell and that my oil pressure was about half of what it normally was ... drained the oil/gas mixture, refilled, and the engine ran better than ever before. Worked like a charm!!! Just glad I didn't somehow get an errant spark in the crankcase while I was driving it ...

Mikes reply :

I am the one that originally said to put 2 gal Trans. fluid in to clean a motor, because a Trans. mechanic took a new motor and after break in with oil, drained it and went 300 k miles and when he went to rebuild the motor it was as clean as new.

The problem with my vehicle is not because of the cleaning with ATF, I only said that I won't discount that I used it several times while I was diagnosing what the true problem was. People like to take things out of context to prove their point...

Secondly, I had a fuel leak in a motorcycle that got into the cylinders through the intake valves, I did not know it at the time but I was running the bike in the driveway with gas in the oil. It was a 1984 Honda 700 nighthawk with oil that runs through the frame to the cooler and back. It did not hurt anything, thank God...