Adding qt of ATF @ each oil change?

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Sep 24, 2002
This was a curious one someone passed on to me - claimed it was good for the health of the engine and was an old timers trick. Personally I never add anything but plain old oil but thought I'd throw this urban legend out for discussion...

you can use atf (I wouldn't use a whole quart) as an engine cleaner before changing oil. I've fixed stuck lifters by doing that.
do a search, beat to death in the past

ATF is a 10W. Not many cleaners and different additive package than motor oil. No special cleaners are in ATF. Essentially the oil timers are thinning the oil for draining. If this thinned oil makes the car better, consider a real cleaner.

Want clean? Use AutoRx.
Want to stay clean? Use synthetic oil.
Keep the ATF in the AT.

My .02$
Don't do it. (as Pablo says). It has a weaker detergent (cleaning) package than regular engine oil. Use AutoRx.
You'll talk to folks who have done this for years and say that they've never had a problem. It washes out some dirty oil.

Well, yes, and so would a quart of the same engine oil they're planning on using, especially if they thin it in a bucket of hot water. The small amount of dirty oil left in the sump after a drain is not significant.

ATF has nothing good in it for flushing an engine. Save your time and money.

MrHonda, please explain the BSS comment,.
Just a point of curiosity guys - personally I don't want to do anything except the occasional oil and filter change w/ plain ol' API certified motor oil.


Originally posted by Pablo:
do a search, beat to death in the past

Pablo, I DID do a search using key words like ATF and Dexron and came up w/ very little and nothing specific to adding ATF to the engine. If this has been beaten to death - was it beaten using other key words besides ATF? Please be specific because the search engine is certainly specific (and a great source of info).

Thanks Pablo,

It was never originally mentioned to me as a "flush" and I did not use the term "flush" when I did my original search. The person mentioning it to me simply mentioned adding it at each oil change as I said.

Am reading thru those links presently - thanks again,

[ September 19, 2003, 03:00 AM: Message edited by: pgtr ]
pgtr, I ran a '73 Chevy 350 some 150000 miles adding one quart of ATF in liew of one quart of oil at changes. I didn't do it every oil change but every now and then letting the appearance of the aging oil be the determination. The engine cleaned from extremely dirty (it had 100000+ when I bought it) to very clean and stayed that way. I was working the truck by regularly towing a 6000# trailer though hills and heat. I thought that using the ATF was a good move judging by my results. Of course, the 350 was a lot looser engine than the modern modular ones of today are.

This is not a recommendation for you or for anyone to do the same thing. I did it because I was desparate to improve a bad condition with the vehicle and was prepared to take the consequences of a failed engine if it had come to that which it did not.

Thanks. Yeah I had heard that just adding it occasionally at oil change was 'good'. Just looking for a sanity check. Those links were interesting reads. I should have mentioned I heard this in connection w/ older engines precisely like your example - it stops or avoid things like problems w/ lifters and such...? I guess it acts as a flush in a way though arguably not ideal.

This is just one of those things like putting a sacrificial penny on your battery or squirting water in your carb - it may not be pretty to a purist (no pun intended) but many swear it works.

I'd rather use Auto RX or neutra or something well respected on this board. No snake oils for me.
Only suggestion I like is when my doctor recommended I have a glass of wine with lunch every day.
Personally I have never done this and never would. Sounds like something that could surely cause engine warranty problems.

If you use good oil and filters, what can be in there to flush out.

But all this talk begs the question, what type is best?



From a data sheet for ATF


Superior cold temperature performance characteristics. Wide range of seal compatibility. Excellent
wear protection. Superior frictional characteristics with excellent friction retention, and smooth shifting.
Fortified against rust and corrosion. Excellent oxidation resistance. Meets requirements for foam
protection. Dyed red for easy identification.

Not a hint of the detergency characteristic??

[ September 19, 2003, 01:49 PM: Message edited by: Mike ]
The current lot of ATF (hydraulic) fluids contains lots of friction modifiers and very low additive levels. The Group II+ to Group IV/V fluids are 0W20 weights.

Use Neutra, LC, or Auto_RX for engine cleaning and leave the hydraulic fluids for hydraulic applications.

Originally posted by pgtr:
This was a curious one someone passed on to me - claimed it was good for the health of the engine and was an old timers trick. Personally I never add anything but plain old oil but thought I'd throw this urban legend out for discussion...


Here's a list of the additives in ATF:
Dispersants: Sludge & varnish control
Antioxidants: Prohibit oxidation
Antiwear: Planetary gear, bushing, thrust washer protection
Friction modifier: Modify clutch plate and band friction
Corrosion inhibitor: Prevent corrosion and rust
Seal swell agent: Prevent loss of fluid via seals
Viscosity Improver: Reduce rate of change of viscosity
Pour Point Depressant: Improve low temperature fluidity
Foam inhibitor: Foam control
Red dye: Identification

Even if some of these components sound good for an engine (dispersants, antiwear) every engine oil has the right products in the right quantities to do the job better that ATF.

In the late 60's I worked part time in a Chevy dealership in a small town. The service manager would occasionally add a small Coke bottle (6.5 oz) worth of ATF to a car's crankcase. This was usually done to try to unstick a hydralic lifter without resorting to surgury. He would then let the car idle for 15 min's then change the oil.
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