Motor oil in trans

My old shop teacher once told us that if you were to rate transmission fluid using the engine oil viscosity scale, it would be equivalent to a 7w14 motor oil. There are a number of friction modifiers blended into transmission fluid that engine oil does not have so I would be leary of using a full load of engine oil in the trans. Maybe a pint or two for topping up in an emergency but not a complete fill. Can't say if the lack of those modifiers would make the trans more likely to slip or grab, but if this really was engine oil, I would suggest pulling it down and have a look while it's out of the vehicle.

When the 727 was new and transmission fluid wasn't as sophisticated as it is now many racers ran straight motor oil in the 727, either 10-30 or straight 30 weight.

One of my best friends has been a trans man a long time,and has been to many a class. At some of the class's they stated that when putting a valve body and other parts to use 30 wt and gear oil mixed 50-50 as an assembly lube

motor oil in a transmission ?
NO WAY !

Was in the Air Force for 20 years, as a Vehicle Mechanic. Most of the larger trucks that had Allison transmissions in them, used 10 Wt (Hydraulic oil). Never had any major failure that I can remember because of the fluid. I know it's not engine oil, but it's along the same lines with different characteristics.

I'm positive it's motor oil. To thick to be atf. And smells different. I didn't have time today to pull out the valve body. But in the morning I plan to take it out and hose the inside down with brake cleaner. If it's burnt atf I should see some nice pretty blue metal in there.
I was thinking when I seen that that it might have been done to solve a problem. Like how they used to add sawdust to the atf.

We usually add a qt of 30w non-detergent oil to type F fluid in our trans. Have also used hydraulic oil with some success. Tranny fluid is a poor lubricant and the motor oil helps lube the bushings.

Also,put your motor oil in anything but a 904/727 and see how long it lasts.Even Type F is not recommended.

The first Fluid Drives that Chrysler made not only used motor oil but it used the same oil as the engine it was attached to, they shared the oil.

While the Fluid Drive wasn't an automatic, per se, it did have a torque converter and other features present in what we call an automatic.

As for switching from gear oil to ATF in a stick, that was done to ease shifting, NOT for durability.

on the flip side Chrysler changed the spec from ATF to motor oil in some of the FWD 5 speeds, durability reasons were given.

ATF is thin, lack of "shock" ability is part of it's problem. As for autos failing for lack of lube, I have rebuilt more than on Torqueflight that had wear issues with bushings. That wasn't teh failure mode, but it was an issue.

I tore apart a 727 that someone put two bottles of "trans fix" in it.The fluid looked like black jello.

I use tranny fluid in my engines, motor oil in my tranny's and brake fluid in my power steering, in the appropriate quantities, of course.
-dulcich

I am working from memory
and don't recall all the details
but I am pretty sure that
Bill Kondolay (of Diesel Trans in Canada)

http://www.dieseltrans.com/phpBB/index.php

several years ago ran some experiments
on 47R automatics
comparing
Mobil One Syn motor oil (can't remember viscosity)
against
Chrysler ATF+ (can't remember whether +2 or +3)

I have a vague memory that it initially looked promising for Mobil One Syn motor oil but did not work out well in the long run

Many years ago I had a good & imformative telephone conversation with an engineer at Universal Lubricants, the makers of the 'Red Bottle' and 'Black Bottle' trans additives about what alternatives would be superior to ATF+2, and this UL engineer seemed confident that Black Bottle additive plus Mobil One Syn ATF was at least as good as +3

Chrysler & Lubrizol laid out the
ATF+4 (Type 9602)
technical story in a 14 page SAE document (paper# 982674)

anyone ever run a 727 or 518
on a test stand for transmissions
and found the friction differences
between the various ATF's
like Type F versus 7176 versus Mobil One Syn ATF ?

From a Harley web site
First of all I want to state that I'm no engineer and the observations here are from personal experience and 40+ years as a auto and bike repair shop owner/mechanic. In the last 30 years I've built well over 1000 automatics for every application from stock to all out race applications in 1000+hp race cars and monster trucks.

For those of you (including myself) that use ATF in the primary here's some facts that I have verified over the years.
There are approximately 25 types of ATF but I'll cover the 5 most common as the other twenty are either obsolete or very vehicle specific.

Type F or (Ford) fluid was developed for and used in Ford automatic transmissions back when the clutch discs were made of sintered bronze or asbestos and there were no bearings used. All parts were supported by bronze bushings and thrust washers. It is essentially 20wt hydraulic oil (pure mineral oil) with a red dye and that's it. It is commonly sold as Racing ATF under brands such as B&M Trick Shift because it provides the quickest lockup of the clutch packs (Hardest shift). It has no place in 99.9 percent of modern applications unless you're just looking for neck snapping shifts (or in the case of motorcycles used for drag racing where quick and harsh clutch engagement is the primary goal and you're gonna change it very often.

Dexron II and III are the most commonly used fluids with the only difference being additives in Dexron III to make it more compatible with the electronics used in modern transmissions.
They both have an additive package that includes friction modifiers for smoother cluch engagement, oxidation control, viscosity stabilizers, corrosion inhibitors and proper lubrication of bearings and bushings of all types. Since the advent of gerotor pumps and better friction materials such as Kevlar and Aramid, Dexron II or III has even replaced the use of Type F for racing use by most transmission builders.
Dexron III is commonly used in many automotive manual tranmissions and is probably used in more transfer cases of 4WD vehicles than any other fluid.

ATF+3 uses higher quality base oils with the highest content of friction modifiers to prevent torque converter shudder. It lubricates a bit better than Dexron III but can also cause slow clutch engagment (slipping). If you ride easy and your primary goal is smooth clutch engagment then this is the fluid to use in your primary if you're gonna run ATF.

Synthetic ATF comes in many formulations but the most common is Dexron III. It has the same properties of clutch engagement as Dexron III with some advantages.
The main advantage of synthetic fluid is it's ability to resist thermal breakdown. If you ride in extreme heat or just want to extend your primary fluid change intervals then this is probably your fluid.

You may want to think about this too. Although the primary doesn't generate much heat in and of itself that's not the only concern when choosing a fluid.

The primary on your motorcycle is not a seperate entity. It is attached to the engine and it acts as a giant heatsink for that engine. The temps seen on a long hard run are probably within 20-40 degress of the engine oil temp.

Mineral based ATF starts to break down at around 220 degrees and is almost useless as a lubricant at 250 degrees.

Personally I use any major brand of regular Dexron III and change it out every 5000 miles but if I did alot of the riding described above I would probably use synthetic (although I am a cheap old [Edited by Moparts - Keep it clean]).

I'm not promoting the use of ATF in the primary!
But!
ATF has proven itself in hundreds of millions of auto applications and tens of millions of manual tranmissions and transfer cases.

You almost never see a 4wd transfer case failure anymore and I've personally seen 4wd trucks with a quarter million miles on a manual transmission and transfer case using Dexron III and still going strong.

Brake fluid will help keep the seal swollen and soft to prevent leaks. I've used it in a tranny that'd hardly pull before, it worked great for about a week.

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I've never heard of putting sawdust in an auto; I know guys would do it to quiet a noisy stickshift, but, I'd imagine that it doesn't do a torque convertor, clutches/bands, front pump, etc. any favors.

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Before the invention of Transmedic the old trick of adding saw dust was to get you home or to sell a car before the trans went. It didn't last long but it got the guy away from your house. And no I never done that. But back to my trans. The clutchs and bands didn't look that good at tear down. But I have plans on rebuilding it anyways. I was more worried about the vb then anything else.