Tranny fluids - what's the difference?

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GreeCguy

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Howdy fellow oilers. You might remember the famous "Luv machine" with it's leaky transmission. (For those who don't - 1986 Chevy Astro Van, 4.3 V-6 - 700R4 tranny that leaks. Van is NEVER driven on the road but is the farm "mule" on my parents 15 acre property).

Until recently, I've been topping off transmission with some old 40 weight motor oil I've had for ages. Transmission seems to enjoy this heavy brew and has been working well.

Now, after doing a transmission filter change and fluid flush on my '93 Ford Taurus, my '95 Oldsmobile Cutlass and my daughters '97 Oldsmobile van, I find myself with almost eight GALLONS of used tranny fluid I plan on using in the "Luv Machine." (All of it is Dex III/M).

This weekend I'm going to help a buddy do a fluid change and flush on his Honda Van. He already has the fluid, (which he ordered from Honda, so it's not something he picked up from Auto Zone or Advanced Auto). I told him I want to keep the old fluid which is perfctly fine with him.

Additionally, I want to do a filter change and fluid flush on my wife's 2004 Chrysler Sebring, (so I'll be buying enough ATF-4 to do a complete flush).

Long story short, I'm going to end up with several gallons of used Honda ATF and several gallons of used ATF-4.

Question: What are the differences in these fluids? Obviously they are all transmission fluids, but why does one transmission require one kind of fluid while another requires another? Are transmissions that radically different that they require radically different fluids?

Secondly, what is the "danger" of mixing these fluids and using them in the transmission of the "LUV machine"? I've used the 40 weight in the past and am now using the used DexIII/M. I'm thinking if it can survive that wicked brew, it surely should be able to function with a few extra adds from different sources.
 
Ask yourself if you have the money to fix the astro's tranny. If the answer is yes then use whatever fluid you want to,if you cannot afford to fix it then I suggest using the proper fluid.
 
1.) Different viscosities and additives to acheive certain shift characteristics. 2.) You can mix those and put them in the "Mule", cannot be worse than engine oil for the tranny. Just my 2c.
 
I should has posted this in the original post.

1. I have created a "catch pan" for the leaking tranny fluid which works very well.

2. Van is not worth fixing. It has no windows, no doors, motor runs but is worn out. The front main seal leaks and while the seal is a 10 dollar part, (according to the "Advanced Auto" website), it would be a lot of work for me to pull the tranny, remove front seal, replace front seal, reinstall tranny.

3. Back in November of '09, it spun two of the rod bearings, (while pulling a tree out of the ground). I dropped the oil pan and installed new bearings. The two that spun were so bad that even with new bearings, there was still play between bearing and rod cap. I mixed up a batch of "JB Weld," let it sit for about an hour until it had hardened to the consistency of "play dough," rolled it out and placed that between the bearing and the rod cap. Everyone said it wouldn't work. I let it sit a week to harden, then reinstalled the pan. filled motor with oil, cranked it up and have been using it weekly ever since. I even wrote the "JB Weld" company and told them this story, thinking I would become the poster child for their product. They wrote back with the simple reply, "We're glad our product worked for you." So much for fame and fortune.
 
Originally Posted By: GreeCguy
Back in November of '09, it spun two of the rod bearings, (while pulling a tree out of the ground). I dropped the oil pan and installed new bearings. The two that spun were so bad that even with new bearings, there was still play between bearing and rod cap. I mixed up a batch of "JB Weld," let it sit for about an hour until it had hardened to the consistency of "play dough," rolled it out and placed that between the bearing and the rod cap. Everyone said it wouldn't work. I let it sit a week to harden, then reinstalled the pan. filled motor with oil, cranked it up and have been using it weekly ever since. I even wrote the "JB Weld" company and told them this story, thinking I would become the poster child for their product. They wrote back with the simple reply, "We're glad our product worked for you." So much for fame and fortune.


Priceless!
crackmeup2.gif
thumbsup2.gif
 
Originally Posted By: GreeCguy
Question: What are the differences in these fluids? Obviously they are all transmission fluids, but why does one transmission require one kind of fluid while another requires another? Are transmissions that radically different that they require radically different fluids?

Secondly, what is the "danger" of mixing these fluids and using them in the transmission of the "LUV machine"? I've used the 40 weight in the past and am now using the used DexIII/M. I'm thinking if it can survive that wicked brew, it surely should be able to function with a few extra adds from different sources.



The main differences in transmission fluids are the friction characteristics. An ATF+4 fluid will have more friction modifiers than a DEXIII/MERC fluid will, and the Honda Z-1 fluid will have even more modifiers than the ATF+4. What this means for your 700R is the ATF+4 and the Z-1 will allow more clutch plate slippage during shifting which in your case would be bad.

If your trans really is operating better with the 40 weight motor oil (typical ATF is the viscosity of 20 weight oil), then I think you'd be better off using ATF F fluid for topping off. This fluid has little to no friction modifiers and may prolong the demise of this already "walking dead" trans.

P.S. - Thank you for being the new GearHead Tool. Your posts bring many laughs to many people here.
 
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The biggest differences among ATFs are the friction modifier additives. These additives interact with the clutch materials the manufacturer has chosen and the shift programming (either software or the hydraulically controlled apply rates in old transmissions) to achieve shifts that will feel reasonably smooth without tearing up the clutches. Friction modifiers are also tremendously important to keep torque convertor lockup clutches from shuddering and tearing themselves up.

For a farm mule, its probably not a big deal to use the "wrong" fluids since its a) not going to see big loads most of the time, and b) probably won't ever get into 3rd gear, let alone apply the lockup clutch. The mere fact that its survived with its fluid diluted with used motor oil proves that it can take a lot of fluid abuse :-/

That said- you're definitely increasing the probability of failure sooner rather than later. Especially with the used motor oil.
 
Originally Posted By: GreeCguy
Howdy fellow oilers. You might remember the famous "Luv machine" with it's leaky transmission. (For those who don't - 1986 Chevy Astro Van, 4.3 V-6 - 700R4 tranny that leaks. Van is NEVER driven on the road but is the farm "mule" on my parents 15 acre property).


If your Parents get their drinking water from a well on the property that the so called "Luv machine" is operated on you may be slowly poisoning them to death by polluting their water table with petroleum based chemicals. You could also be putting their farm animals and neighbors at risk as well. One quart of motor oil or atf will pollute 1 million gallons of ground water to the point where it is poses a serious health risk to anyone who ingests it. Fix the leak or junk the vehicle.
 
Originally Posted By: Doog
Originally Posted By: GreeCguy
Howdy fellow oilers. You might remember the famous "Luv machine" with it's leaky transmission. (For those who don't - 1986 Chevy Astro Van, 4.3 V-6 - 700R4 tranny that leaks. Van is NEVER driven on the road but is the farm "mule" on my parents 15 acre property).


If your Parents get their drinking water from a well on the property that the so called "Luv machine" is operated on you may be slowly poisoning them to death by polluting their water table with petroleum based chemicals. You could also be putting their farm animals and neighbors at risk as well. One quart of motor oil or atf will pollute 1 million gallons of ground water to the point where it is poses a serious health risk to anyone who ingests it. Fix the leak or junk the vehicle.


Yes, you're right, and I have made a catch pan that hangs under the transmission that works very well. Inside said catch pan is a "sandwich" of shop rags and cardboard that takes up the entire bottom of said catch pan. It works very effectively and while I haven't done it, it's a very large temptation to drain oil/fluid from "sandwich" and pour it back in tranny. I figure you have to draw the line somewhere.
 
That JB weld story is priceless. The kind of stuff you are doing sounds like something that would happen in a situation where no replacement parts are available and one must use only what is laying around. I say good practice for if that ever happens. Not sure I would spend a ton of time on that endeavor. I also was concerned about ground water contamination but it sounds like you have already addressed that concern.
 
This is hilarious.

Having grown up on a farm, and having experienced plenty of time with my own "Luv Machines" as you say, I can say this...

I'd easily be dumping that old ATF in your van because I wouldn't give a [censored]. ATF+4 is a thinner and has more additives, the Honda fluid I'm unsure, but fundamentally they're all hydraulic fluid and will all do the same trick. Probably not perfect for road cars and probably could be hard on the transmission, or make it shift funny, but it'll move around and that's all that matters.

People worried about the ecological damage are just jumping on you, I'm sure you're fine. Fixing the actual leak is a waste of time in something like that. I wouldn't even dump a bottle of stop leak or something thick to even attempt it, since the thing is just a farm pig anyways.

People suggesting to actually buy new fluid also likely have no experience with such a vehicle. If you're like me, you probably don't even wanna buy gas for the thing, so long as it keeps the party going in some way.

Kudos for throwing bearing yanking out a tree though, that had to be a fun day, lol. Nice to hear it takes a lickin' and keeps on tickin'.
 
yes use it in the van tran.
And you can also burn it by mixing into the gas, not ot exceed a QT IN 20 gallons. I have done that in my 94 RMW buick to use up old ATF. Old ATF mixed intop old gas also keeps gums from sticking valves.
 
Originally Posted By: GreeCguy
"P.S. - Thank you for being the new GearHead Tool. Your posts bring many laughs to many people here."
thumbsup2.gif
 
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