Adding ENGINE oil to Auto Transmission

[Devildog]

synthetic motor oil!

I spoke to Bill K. a while ago he said it was common, but synthetic only...

 

[Dieselnerd]

Dave Goerend recommends it for towing.

 

[Vaughn MacKenzie]

Devildog, I meant to mention, the transmission builder I talked to said to use synthetic motor oil.



TKilgore, this guy drags his '69 'Cuda and if his transmission didn't shift OK he wouldn't be adding motor oil to it. He thought the main concern regarding shifting is in very cold weather. . . the oil may be a bit thicker and make the transmission slightly more sluggish, however with synthetic 5W30 the pour point is around -60F so I wouldn't think that would be a problem.

 

[amsoilman]

ATF requirements are set by the manufacturers of the equipment ie. Chrysler, GM, Ford, etc .

ATF fluids are usually a multi-viscosity hydraulic fluid. Dexron II & Ford Type "F":5W-20

Dexron III, Mercon V & ATF plus 4: 0W-20.



These fluids are very different in terms of frictional characteristics. The degree of slipperiness for the Chrysler ATF Plus 4 for example is "Moderately" slippery, compared to the Dexron II & III, Mercon V as it is "slippery". The Ford type "F" is "grabby".



The coefficient of friction of a fluid will affect the shifting characteristics of the automatic transmission, so adding motor oil could change this. Remember Viscosity is the single most important characteristic of any Lubricant!

Another important characteristic of ATF is its ability to resist Oxidation. GM study several years ago indicated that 170-175 degree F. was the "normal" operating range and for every 20 degree increase in temperature above that, the life expectancy would be cut in half! Oxidation increases with temperature.



Then there is the cold temperature characteristics due to the extremely narrow passage ways in the transmissions electronic shift selectors and valves. If the fluid doesn't flow well in cold temperatures, the transmission won't shift properly until it gets warmed up. There are other important characteristics as well such as "pour point", "Viscosity Index", antiwear, flash point, fire point, antifoaming ability, demulsibility, and acid neutralization. To be very specific, ATF is a very complex fluid!



In general it is never a good idea to mix two different oils in any application. If this is unavoidable, there are two major concerns, specifically incompatibility between the base oil, and incompatibility between the additives. The overwhelming majority of synthetic oils, particularly crankcase oils are PAO based. From a base oil standpoint, there are usually no problems with mixing a PAO synthetic and a mineral oil since both are hydrocarbon based and chemically very similar. However, extreme caution should be used if the synthetic oil is non-hydrocarbon based.



As for additive incompatibility, the biggest danger is mixing oils with very different additives packages, particularly mixing those with acidic additives, such as most (AW)Hydraulic and (EP)Extreme pressure oils, with oils containing alkaline additives commonly used in crankcase oils. In this case, mixing can result in a number of problems including additive drop out, loss of demulsibility, foaming problems and reduced oxidation stability.



The best approach is to select the appropriate lubricant for the application at hand and stick with it! If you are forced to mix oil of different types,then be careful and make sure you know what your putting in.



Personally I just use a very high quality synthetic ATF and leave all the additives out!



Wayne

amsoilman

 

[Waterpete]

I have used 25% motor oil of the total volume of the transmission fluid for three years with no problems. An old transmission guy recommended it. I did try using straight 30 weight motor oil, no transmission fluid and did some towing runs measuring heat and et's but found no difference with either motor oil or transmission oil. I use the cheapest straight 30 weight I can find. I now add 4 quarts of motor oil at transmission fluid changes.

Works for me!

Pete

 

[lgibson]

ATF is 90% detergent. It suspends contaminates in the oil so it does not stick to any surfaces to cause problems. Also if you go without changing your ATF for a long time, 60,000 miles or so, and you change it you risk the chance of burning up your transmission. The fresh ATF will strip the clutches clean in a few hundred miles, I seen it many times. Put your hands in some old motor oil that has been in a old diesel, you know the kind with a lot of soot. Know wash your hands in clean ATF. It cleans beter than hand soap. We clean our shop floor with the stuff.



ATF is a science now days. These old tricks worked in their day. In their day there were no computer sensors and solinoids to screw up. The only thing I will put in a customers trans. or in mine is Lubegard in the red bottle. Been doing it since 1988.



BTW Alison's uses motor oil in their transmissions. Not to sure about their baby trans. in the Duramax.

 

[Texas Diesel]

ATF is used in our transfer cases too. Why? A person on the TDR who is/was into Jeeping told me that the Jeep guys have been running synthetic motor oil in their transfer cases for a long time with excellent results. I know there is little in common between transfer cases and auto trannies but seems to fit the question asked above as to why DC wants ATF instaed of motor oil. One reason I have been told is that ATF is extremely high detergent to keep the slush boxes clean.

 

[Shooter]

I'm not a transmission guy but I worked in a shop that was also an Allison dist. They had a transmission reman facility ( 300's to 900's ). All company trucks

were equiped w/ autos. All autos were filled with Delvac 1300 15w40 same as he engines/ gas and diesels as soon as they were out of warranty.

If you mix oils it is no better than the lowest rated oil. If the atf is lower temp rating than the mix then the atf will still fail at the lower temp. ALL OR NOTHING

 

[fredflinstone]

Adding engine oil to automatic transmission?

I am also curious as to why the recomendations for automatic transmission fluid in manual gear boxes and transfer cases?? And what the diference is with the people runing synthetic motor oil in them?? Does anyone know the difference in doing either of the above and what the benifits are from switching to motor oil as some members have done???

Thanks Seth