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Thread: OT: Mixing ATF with motor oil
01-07-2007, 07:52 PM #1
Greetings & Happy New Year -
An aquaintance, one whose theories I frequently have doubts about, strongly recommends that when a car's engine oil is down by one quart it be topped up with a quart of ATF. He claims that this will do an excellent job of "cleaning out" the engine - of sludge, I guess he means - he tends toward vagueness and generalities when asked for details on why this should work, but is adamant that it does.
I'm pretty skeptical on a couple of counts.
First, as I understand them, the roles of ATF and motor oil are quite different - motor oil needs to have excellent lubricity to protect the many sliding interfaces in an engine, pistons to cylinder walls and rod bearings to crankshaft just to name a couple, and also to contain detergents and neutralizers to deal with the products of combustion, such as acids and soot, while ATF actually requires a limited and controlled level of lubricity so that wetted clutches and bands in automatic transmissions can grip without excessive slip and so that synchronizers in manual transmissions, most of which now call for ATF, can operate with enougn friction to sychronize. In fact, it's my understanding that an automatic transmission cannot operate properly with motor oil in it due to clutch and band slippage. Also the compounding of ATFs need not be concerned with the harsh problems posed by combustion product blowby.
Second, it seems very unlikely on the face of it that ATF contains a better additive package for keeping an engine sludge free than does a good quality motor oil formulated with sludge control as one of its primary objectives - sort of like the old claim that a roll of toilet paper could make a better oil filter than a product specifically designed to filter oil - I never bought that one either.
Recognizing that even at my age I may still be able to learn something new, and remembering that once or twice in the past I've been mistaken, I'm asking fellow forum members if they know anything about this topic. I'd be particularly interested in information, pro or con, that you are aware of from reputable engineering sources in the automotive or motor oil industries.
Hope some of you can offer worthwhile thoughts on this.
01-07-2007, 07:58 PM #2
I presume that this is immediatly before an oil change. Sound like rubbish to me. Buy some flushing oil and do a proper job.
01-07-2007, 08:05 PM #3
I have heard that one before, and it was to be relatively close to oil change. I have done it with no apparent ill results.
01-07-2007, 08:10 PM #4
Good point guys - how far before the oil change wasn't clear - seemed as if he meant the last top up required before a regularly scheduled (e. g. 5000miles/six months) oil change.
01-07-2007, 08:11 PM #5
Not saying it's a good idea at all, but I used to work for a very reputable mechanic who knew some nut that had rebuilt a station wagon engine and filled it with ATF. Said he was very skeptical at first, but apparently the car ran just fine that way for many years!
Myself, I'll stick with motor oil for engines and tranny fluid for trannys.
01-07-2007, 08:17 PM #6
From this page at Quaker State:
Adding a quart of ATF the day before an oil change will clean your engine. ATF added to the motor oil will clean the engine due to the high levels of detergent in ATF.
ATF does not contain detergent chemistry. ATF does contain dispersants, which have properties similar to detergents. But ATF is not formulated to withstand the combustion environment inside the engine. Quaker State® recommends that you keep the fluids where they belong: motor oil in the crankcase, and automatic transmission fluid in the transmission.
01-07-2007, 08:17 PM #7
It is encouraging that there were no adverse results.
If one uses a decent oil and changes oil and filter regularly, sludge should not be an issue.
01-07-2007, 08:23 PM #8
The fluids have different ways of dealing with contaminants.
Engine oil you want to carry them in suspension to the filter.
Millions of transmissions with no filter (not counting the screen), the contaminants need to settle to a quiet area.
I'd venture that 50% of the people who have purchased a transmission flush have also purchased a new or rebuilt transmission (this is just from talking to a small number of people and taking mental notes).
The problem is the flush stirs up all the settled-out junk and it overloads the suction tube to the point of clogging it, and the mechanism doesn't do well from a longevity perspective with no lube and no pressure to keep the clutch packs clamped together.
01-07-2007, 09:03 PM #9I'd be particularly interested in information, pro or con, that you are aware of from reputable engineering sources in the automotive or motor oil industries.
With one proviso - be wary of old manuals. For example the manual for my 1959 John Deere 430 recommends flushing the engine if sludge appears, using cleaning solvent or kerosine, run for a few seconds and drained - however, I would take a guess that JD no longer recommends this - some information goes out of date. Oils and practices have changed.
I have seen what engine flushing can do - a friend was advised to use flushing oil (strange, the 'friendly' mechanic happened to be selling the very product!). Turned the old engine (1961 Holden) into an instant undrivable oil burner, I got the job of re-building it.
This just touches on what is a part of everyday experience. I usually want to know what is 'best' when buying a product and weighing up the options with as much info as possible. However, have come to realise, there is a huge part of the population who not only don't do this, but (this is the weird part) are actively resistant to any type of 'science' when making decisions of any type (automotive, appliances, medical whatever). I will go further and say they are proud of their 'independence' of choice. Interesting, eh. Must give great hope to advertisers everywhere!
(I am only scratching the surface of this subject - consider the large group found on this forum - the only recomendation needed is that it was told them by a workmate, preferably older, extra value if a relation, say father. Instant Facts!)
Sorry, back to those oils....I think my Dad would maybe recommend a bit of whale oil in there.
01-07-2007, 09:06 PM #10
A little OT but I bought an Olds Omega from a co-worker for $50 about 8 years ago. He had driven it into work but it ran very rough and he was tired of it. I had 2 teenage boys at home at the time so I thought it would be a good project for them. We towed it home and put it in the garage. Pulled the oil dipstick out and found it was about 2 inches over the full mark and smelled of gasoline. Drained the oil and it ran out like water, scared it was going to overflow the pan. We rebuilt the carb and it ran great. I bet the cleaning it had got with all the gas in the oil had gotten rid of any sludge. It didn't use oil and the boys put thousands of miles on it. It wasn't very stylish tho so we ended up giving it to someone who needed transportation.
01-07-2007, 09:18 PM #11
I've heard of doing things like this on my side of the pond, some freinds in the engine recon game warn about flushing oils on anything, over here the favorite is clogged hydraulic lifters, and on certain models blocked camshaft oilspray pipes.
I've seen their ''graveyard'' to prove it, lobeless cams and .125" deep scores in journals, no need to describe the cam bearings.
I've seen VW Golf (Rabbit to you) cranks where through blocked oilways the shells have spun in both block and rod housings.
Our ''Rover V8'' (3.5 to 4.6 litres) and originally a Buick, doesn't take too kindly to it either, all the crud in the timing chest chews them up a treat.
Like I say, if it ain't broke don't fix it!
01-07-2007, 09:27 PM #12
i almost hate to say so, but i HAVE used atf
in an engine with benefit. ok... a 1989 mazda 626
had a sticky lifter(s) , the thing had 150k on it
and sounded like a freakin' sewing machine .
a casual friend/mechanic suggested i drain out
some oil and replace it with about a quart of atf
and drive it that way for a week or so.....
i thought it was total BS , but did it anyway ...
it took about 200 miles of driving , then the
ticking stopped! i changed the oil soonafter ,
and the hyd lifters were still quiet when i sold
that car 12k miles later.
i wouldn't just pour some in for kicks though.
but it did help sticky/noisy lifters .
VW Golf (Rabbit to you) nope it's been the golf
here as well...i bought one new in 1985 when the
rabbit was replaced..22 years ago.
01-07-2007, 09:32 PM #13
Read somewhere, here I think, that Marvel Mystery Oil is largely ATF. If that's true, adding it to engine oil has to be bad, eh?
I used to use MMO on my (noncritical) wire rope winch cables, until I bought some proper wire rop lube. It was ok for keeping them flexy and reasonably corrosion-free.
01-07-2007, 10:04 PM #14
Bull$****. Automotive lubricants are formulated to optimize their performance in engines and transmissions. Fortunately nothing drastic happens when meatheads try to fix what aint broke by mixing oils.
Wanna keep a clean engine? Change the oil regularly particularly in stop and go driving.
The black butter that accumulates is there because the change intervals have been neglected. I've seen well maintained engine with 300,000 miles on them open up black but relatively clean. OTH neglected engines having 100K or so can be completely occluded with "butter baffles," holes in a continuous accumulations of sludge with openings for the working parts.
If you want to know and understand more about lubricants and their selection DON'T ask a guy at the auto parts counter, a peddler of car remedies, guys with speed company decals in their windows or tool boxes, or guys who read auto magazines. They spread BS about lubricants that floats around masquerading as Gospel truth. They may be well meaning but don't trust them; 99% of them are ingorant as a pine stump.
Look in the professional literature and the lubricant engineers for your best guide for the of selection lubricants.
I've been a machinist for many years which should give me some expertise in the matter of lubrication. Funny thing. I've made some mistakes that shortened the life of the equipment but I've never accrued a single significant success by over-ruling manufacturer's specs. Now I follow manufacturer's directions for lubriction and use one of the many cross indexes to refer call-outs to my preferred suppliers.
If you think hunting out credible information needed to make rational choices is expensive in time and money try ignorance and "- a guy told me...".
[ 01-08-2007, 02:26 AM: Message edited by: Forrest Addy ]
01-07-2007, 10:25 PM #15
If and when sombody shows me an auto manufacter
who gives those instructions (put ATF into the
engine) then I might consider it.
In the meantime it's synthetic motor oil, only
if you please.
Oils have changed a lot. *Maybe* that was a
good idea 40 years ago. But not now. Anyone
who's done a teardown on a motor will see that
mostly the insides and the pan are clean enough
to eat out of, with a quick wipedown.
If there's an sludge in there, something else
is wrong, big-time. ATF won't fix that problem.
I would also suggest that the viscosity
difference along implies that ATF and MM Oil
are two completely different critters.
Plus MM Oil has that pleasing minty aroma!
01-07-2007, 10:40 PM #16
I had a 73 ford with sticky lifters. At high idle poured tranny fluid straight down the carb. Got in and tore out of town(down main street). A couple miles out of town and back the old ford was good as new and the cops were looking for a fire(true story).
01-07-2007, 10:58 PM #17
I simply have GOT to wonder how anything going down the air horn, into the intake, through the conbustion chamber, out the exaust port, into the exaust system and out onto the roadway in th3e form of smoke touched, much less had any effect on, the valve lifters' inernal workings....Joe
01-07-2007, 11:03 PM #18
I have a diesel pickup that had two cracked heads. The thing would carry the fuel from two none firing cylinders into the crankcase. So after about 50 miles oil level on dipstick was 1 qt too high or so. Anyway I drove it with this problem for a couple of weeks dropping the extra fluid every couple of days. Talk about cleaning it out! No ill affects and after repairing those heads it took along time for the oil to even look dirty between oil changes. That was 80K miles ago.
01-07-2007, 11:49 PM #19
i rented a truck once , the fanbelt broke ,the
motor got REALLY hot + the truck slowed down and
quit , wouldn't start ....when they towed it in,
the mechanic said the thing nearly seized , but
he had a trick....poured a mix of gas and atf
down the carb, cranked it for a few minutes.
the thing started up! it was still f-u'd ,
but he had it running by the time the replacement
hertz truck came.
01-08-2007, 01:06 AM #20
The only place I've heard of mixing ATF with regular oil is in a manual transmission to help get rid of any varnish buildup on the synchronizers. A Datsun 510 racing book I have mentioned it.