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Trans fluid in oil


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My father accidentally put about a quart of trans fluid in his 97 deville and he refuses to have the oil changed out because of it. Is that going to be bad or is it not a problem?

I am a little confused by your question why does he refuse to change the oil? What does he not want to waste the other 6 or 7 quarts?

I found this:

Speaking of oil changes. If you purchase a used car with a 'questionable' maintenance record, it's a good idea to add automatic transmission fluid to the crankcase and run the engine for a few minutes before changing the oil. This will clean out a good portion of the sludge and build-up from the inside of the engine.

Note the statement "for a few minutes". Personally I don't think I would leave the tranny fluid in. I am curious what others say here.

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shouldnt hurt it it will thin the oil engine will run slighyly hotter and tranny fluid will clean it but i would think u would want to change the oil rather quickly to get the sludge etc out and def change the filter

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I have alway been under the impression that trans fluid is little more than very high dtergent motor oil. Obviously there are some different additives. Many years ago I was told by a mechanic to always short the oil change by one qt. and make up the difference with a qt. of trans fluid. Did that for years. Tell him not to worry about it. It won't hurt a thing.

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My next door neighbor when I was a kid, was an old retired mechanic he always ran transmission fluid instead of oil in his mowers and tractors, he told me it was because transmission fluid held up better under heat and it was just as good as a lubricant as oil but he only used it in air cooled engines. He never had any problems with his engines so I would guess it really can't hurt.Personally I would just change the oil and not have to give it a second thought.

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I have alway been under the impression that trans fluid is little more than very high dtergent motor oil.

I don't think that's true at all....

Trans fluid has got to be closer to hydraulic oil than motor oil. Imagine what would happen if you put motor oil in your trans... would those clutch packs, now lubed-up and coated with "slippery" motor oil even work?

I don't think you'd move an inch smile.gif

ATF applies pressure hydraulically, cools, cleans, and sure - lubricates internal roller & needle bearings but if you've ever seen the stacks of steel plates & "frictions" (clutch plates) that are pushed together to engage in an auto Trans, it is hard to imagine that system being compatible with real, slippery, lubricating oil...

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I was at the caddy dealership today getting my oil change and it reminded me of this topic, I asked one of he menchanics that was doing the change iwhat would happen if somebody put 1qt tranny fliud in by accident. He informed me that is will NO harm to the engine, but if it was him personally he would change it out. I think if it were me also I would Change it out I see it this way Motor oil belongs in a motor and tranny fliud belongs in a tranny.

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An interesting topic. My question is this: Would it be safe to displace (or replace) 4 quarts of oil for 4 quarts of transmission fluid in the engine? If it is then hey that's terrific. But if it isn't (and I assume that it isn't but I'm no expert) then where do you draw the line? I think that it's sometimes too easy to simply say "nah...you'll be ok" but would you feel comfortable doing it to your own vehicle. I can answer with certainty that I would not be ok with that on my car. Perhaps we should be saying "Tell your father that it's not the best idea and you're probably not in any immediate danger but you should change the oil as soon as it's convenient."

The Northstar has strict and tight tolerances and not much room for error and if nothing else it sure is expensive. And if one quart of tranny fluid is ok then 2 qts must be somewhat ok? How about 1/2 a qt of water? wink.gif

"Burns" rubber

" I've never considered myself to be all that conservative, but it seems the more liberal some people get the more conservative I become. "

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Well folks,

To add a little dimension to the subject...

I was in a hurry "one dark and stormy night" and added a quart of oil to the radiator on my '64 Dodge Dart slant 6. I can't recall if drinking had anything to do with it, but whatever...

Some years later...my cousin who had bought the Dart told me the radiator was really gooked up and I recalled the issue. No big deal, just some additional flushing needed. rolleyes.gif

There has to be some degree of "fault tolerance" built into most any consumer product based upon its application/clients - or it just would simply not sell.

I would guess that there is no imminent danger. But of course GM is not going to say OK to anything but whats on the label - or they would get crucified.

I also agree that for the peace of mind etc, just change the dang oil and move on with life.

All IMHO smile.gif

Add power to leave problems behind. Most braking is just - poor planning.
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An interesting topic. My question is this: Would it be safe to displace (or replace) 4 quarts of oil for 4 quarts of transmission fluid in the engine? If it is then hey that's terrific. But if it isn't (and I assume that it isn't but I'm no expert) then where do you draw the line? And if one quart of tranny fluid is ok then 2 qts must be somewhat ok? How about 1/2 a qt of water? wink.gif

I would never argue that 4 qts. of trans fluid is pushing the limit (maybe beyond) and possibly detrimental. 1/2 qt of water, NEVER. But I still maintain that 1 qt. of trans fluid will do no harm. Been there, done that, for many years. Granted, that was years ago and engines have changed but the basics are the same. Bearings, cams and rings have changed little. They still need the same lubrication. The engine will not suffer an early demise.

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I remember someone asked Bbob if 5W30 could be used in place of the recommended 10W30 in order to increase gas mileage. He stated that the recommended oil should be used because Northstar tolerances need heavier weight oil because of its film strength and is better able to protect moving parts. This may be different on the newer Northstars, which I believe use 5W30? The bottom line is to use the recommended oil. He did not recommended using lighter weight oil because lower film strength will not protect as well, especially under heavy load and hot conditions. I think this same logic applies with respect to using transmission fluid. I’m not sure what advantage there is, if any, in using transmission fluid. If the only subject is whether to change oil because a quart of transmission fluid was accidentally used, then I would agree that it shouldn’t be a problem. But as far as regular use of transmission fluid, I wouldn’t go near it. If transmission fluid does a good job at cleaning internal parts then I would think good quality brand oil should do the job just as well. I remember Bbob advising against using oil additives like STP and Slick 50, because he did not feel such products provide any particular advantage and thus, for the most part are just a waste of money. His advice was to stick to the basics.

The only time I remember him talking about using different oil than recommended was with respect to the old 350 pushrod engines. He said that diesel engine oil could be used in these types of engines.

Am I right Scotty?

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As Ranger said I am sure one quart will be OK. Would I do it, nope not on a bet. But then again I am pretty much by the book.

Anyone know the viscosity of tranny fluid? Next time you get a chance, rub some oil between your fingers and then rub some tranny fluid, the tranny fluid feels very different almost abrasive.

One quart out of 8 is only 13%. How might one quart or 13% tranny fluid might negatively impact oil pressure? According to the amsoil site tranny fluid viscosity at 100 degrees is 7.5 and at 40 degrees it's 37.4? It thins out when its hot, that makes sense, I wonder what viscosity it is at 240 degrees? I recall that my oil used to get to 240 in traffic in our 86 Vette. Remember heat is tranny fluids worse enemy. http://www.amsoil.com/storefront/atf.aspx

Kinematic Viscosity @ 100°C, cSt (ASTM D-445) 7.5

Kinematic Viscosity @ 40°C, cSt (ASTM D-445) 37.4

This will be an interesting test for us all to watch. My guess is that IF synthetic oil cleans so well and can cause leaks, tranny fluid may do the same as it cleans all the nooks and crannies not to mention the decreased viscosity. So watch for leaks at the case half, fittings, the 9 year old o-rings, CAM covers, etc. Also watch for oil burning due to oil sneaking by the rings due to the oil being thinner. Also watch for the oil light coming on at idle. Did he use this with 10W30 or 5W30 getting ready for the winter?

One thing I know for sure, I won't see the problems it might cause from my house! laugh.gif But I am sure it will be fine (for other caddy owners)... laugh.gif Hell but who am I, I wear a BELT and SUSPENDERS to keep my trousers up laugh.gif I don't like the roller coaster or ferris wheel because I wonder who maintained it, and my wife calls me Mr. Safety laugh.gif

Most Caddy owners tend to be conservative. Look at the recent post about who maintains our vehicles, I was very surprised how many had their caddy serviced at the dealer. We are a conservative bunch. That is why this subject rubs us wrong.

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There has to be some degree of "fault tolerance" built into most any consumer product based upon its application/clients - or it just would simply not sell.

About 2-3 years ago this girl I know mistook the oil fill port for the washer fluid reservior. When she told me this I wasn't surprised (she's like that) and it gave me a good laugh. She got about 5 miles down the road and had to be towed on a flatbed to the dealer from a mildly seized engine. Sure we all make mistakes now and then but we have only ourselves to blame. But you have to admit some stories of dumb acts are much better than others. laugh.gif

"Burns" rubber

" I've never considered myself to be all that conservative, but it seems the more liberal some people get the more conservative I become. "

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