Adding ENGINE oil to Auto Transmission

[Vaughn MacKenzie]

Last week when I was in Spokane to have Shelley's Automotive install my SBC, I got to talking to one of the guys that works for them part of the time who rebuilds auto transmissions. The topic of trans fluid came up and he commented on how ATF begins to break down at significantly lower temps than engine oil and how its lube qualities are inferior in comparison. ATF begins to break down significantly by 250F or so he said which doesn't give you much margin of safety even if you start to heat up a bit. I don't know much about Automatic transmissions but I have seen graphs showing how quickly trans life is shortened by temp increases over 200F, probably due to ATF breakdown.



He then said he strongly recommends adding 1 quart of 5W30 engine oil to average size trannys and 2 quarts on larger vehicles such as pickups and SUVs. This is to increase lube qualities and raise breakdown temps a bit. He has seen this make a considerable difference in transmission life. He has a '69 big block 'Cuda he drags and hasn't opened up his auto since he built it 5 years ago. He has made 180+ passes per year with no problems at all (don't know how fast his Cuda is though but it is a pretty serious car, I would say sub 12s easily). He says he gets a lot of skeptical reactions to his recommendation but he believes in it.



I thought I'd post this to see what you guys think (especially some of the big Auto BOMBers) or if anyone has heard of this. Sound crazy? Doesn't seem like too bad an idea to me, but then I drive a stick



Vaughn

 

[John]

April Fools, right Vaughn?

 

[Bob Wagner]

I will stick with my Amsoil ATF+4

 

[Vaughn MacKenzie]

Originally posted by John

April Fools, right Vaughn?

Good try John, but I'm NOT kidding!



Bob I meant to ask him about synthetic ATF. I will next time I see him.

 

[Bob Wagner]

Thanks, Vaughn



Are you attending Dyno Day?

 

[Stefan Kondolay]

A lot of my dad's customers in the southern states do this , you would have to ask him for the specifics yourself though. I thought it was kind of funny when i first heard this too.

 

[Wheaties]

Help me out here. If oil is cheaper than ATF, and it would help your transmission significantly, why wouldn't you do it from the outset? Why wouldn't it be in the owners manual and why aren't transmission mechanics trained to do this?



Vaughn, this is not an attack. If someone has an answer, I'd really like to hear it. Like you, I'm a stick driver anyway.



Matt

 

[John]

I thought I remember hearing (or reading) that the oil (engine or gear) would contaminate the ATF leading to excessive slipping with ALL the automatic transmission clutches.



I DO remember when BD used to recommend the addition of a friction modifier (same stuff you would use in your axles) to your ATF to reduce/eliminate shuddering problems. That was several years ago or so... I also heard where it didn't work real well, and for very long.



See! If "you" hadn't kicked Bill Kondolay off this forum he would have given us the facts about this! Not to discredit the auto. trans. rebuilder you met in Spokane Vaughn but...

I wouldn't try this until I received approval and/or blessing from my transmission component vendor if I were any of you.

 

[abledog]

I know of someone that adds motor to his auto trannie with no problems! If he see's this post maybe he will respond?



I just replaced the trans fluid in my 241HD transfer case with Amzoil 5-30! Not sure what the outcome will be? The test will be If it makes it to MayMadness and back towing 13,000 pound.



Terry

 

[merryman]

Anyone know what the technical differences are between engine oil and transmission fluid? An explaination would help this discussion



Vaughn

 

[JHansen]

This brings back memories of a series of articles in Chrysler Power in the late '80's I believe about Torqueflites by a transmission guy named Marv Booth... he recommended the same thing! Until this post came up I'd pushed it off into a dark corner of my mind. I'm thinking I may not be brave enough to try it on my own new truck... ... . but my brother's '98 is sitting outside-maybe I should sneak out under cover of darkness and add a litre of motor oil! Maybe not either.....



It is an interesting topic though.....



Jason

 

[BushWakr - RIP]

JHansen,



Hey I know, you could just say that the porous casting on the transmission, absorbed a large amount of oil from the atmosphere due to the high atmospheric oil content resulting from a southerly wind from the oil fields..... ya, that it... . ya.



Just tryin to contribute to the theoretical/testing phase of auto transmission's.



bob

 

[WeirCummin]

I think abledog is referring to me, even though I do not have a auto in the Ram. I have been adding a quart of syn. motor oil to the wifes Cherokee @ every transmission service since it was new. The fluid gets changed every 10K, 1 Qt. oil and 3 Qts. ATF and I drop the pan @ 40K intervals. The AW4 in the Jeep shifts and drives the same as the day we picked it up new and when the pan is dropped there is very little if any wear metals or clutch lining in the pan. I also run syn motor oil in the transfer case, It is a NVG231 which is the baby brother to the 241s in the Rams. The Jeep has 120K on it. I was one one that talked Terry into running syn. in his T-case.



FLAME AWAY !



Dean

 

[inarush76]

motor oil in trans

Adding motor oil to trans is not a bad idea with regular petroleum based ATF. Just be sure it is SYNTHETIC motor oil. It is used as stated above to address high load/high temp lube. I recommend the use of full synthetic but have had customers that just would not spend the little extra so would add some synthetic motor oil to supplement the ATF. Have talked to some guys that work their truck hard in desert regions (always hot!) and they run their trans full of synthetic oil. Using the mix will give better protection than straight ATF, however the change intervals don't change. With full fill of synthetics you get better protection and extended drain as well. If using any motor oil in trans use only a 5w or 10w-30. Using a thicker oil such as regular motor oil could cause cold weather problems due to some of the small passages in the trans. Just my . 02.



James Northum

 

[BigYellowIron]

That was my understanding also, about using synthetic. I don't think that the Natural oilis compatible with the seals.



I heard it recomended, but only to guys that tow heavy loads all the time.



adam

 

[JHansen]

Hey Bob-have you been looking over my shoulder? Seems you're up to speed on some of my technical research!



This subject does interest me though-ever since I saw the article in Chrysler Power I've been wanting to try it in something-but I've always been too timid... .



J

 

[Dieselnerd]

I've been running 2 quarts of Mobil 1 5W-30 in my transmission since I had it upgraded last summer. I do tow quite heavy and was told that it would lube the OD gears better than straight transmission fluid. I recently towed for 7000 miles with no problems whatever. Next time I change my fluid I will only add 1 quart since some fluid remains after the drain.

 

[Vaughn MacKenzie]

Hmmm, great discussion. WeirCummin & Deselnerd, I had no idea some of you guys already practiced adding engine oil to the AT. When I heard it I thought the idea was a bit bizarre but it made sense to me.



John makes a good point though, I'd check into this more before doing it myself. I'm certainly not recommending it but thought I'd throw this out at you guys and see what sort of responses it would generate

Originally posted by John



See! If "you" hadn't kicked Bill Kondolay off this forum he would have given us the facts about this!

Vaughn

 

[10-G]

I had a small transmission shop service my auto transmission one time when I was away from home on vacation. The owner recommended this and he added a quart of Mobil 1. It worked fine. it has been flushed and refilled since then. I do not remember what grade or weight of oil it was. I have 109,000 on my auto trans, it is smooth as silk.

 

[TKilgore]

Friction

I am probably all wrong but here goes.



In my humble thinking, engine oil has the job of reducing friction and wear. ATF+4 has friction modifiers to reduce friction and make the shifts smoother (slip?). Therefore, oil might help some aspects of the AT but I would think the shift would suffer.



Not arguing, just MHO



Tom



P. S. How many more day till Bill K returns?