Low miles, but OLD car with factory fill?!?!?!

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Originally Posted By: babyivan
Originally Posted By: milkboy
If I'm reading this correctly, the stuff is TWENTY-SIX YEARS OLD.

I don't think it's unreasonable or extravagant to change it out once every TWENTY-SIX YEARS.

If it were that simple, I would not have made a thread about this.

When a mechanic tells me NOT to change the fluid because the fluid has been in the trans. for TWENTY-SIX YEARS, this is what perplexes me. From all of the research Ive read, there are 2 schools of thought on this.

One is to leave high mileage trans fluid alone, changing it will likely cause problems. I will not go into specifics, seeing as it has been discussed time and again!

The other thinking is, that new fluid is better than old fluid... PERIOD, END OF STORY!

My specific query refers to age rather than mileage.

My trans. happens to shift perfect with TWENTY-SIX YEAR OLD fluid and perhaps might not react well to new fluid for whatever reason.

I'm in the process of slowly exchanging said fluid and will end up doing the filter and top off (6.5 quarts out of 11) next month in spite of two different auto mechanics strongly recommending that I leave well enough alone.... the whole "if it ain't broke, don't fix it" line of thought.


The caps weren't directed at you, they were directed at your mechanics. Let me over-simplify further - go somewhere else.
wink.gif


Transmission shops have a tradition of recommending against fluid changes on old and / or high mileage units based on two ideas :
1. It is ready to break, and if we are the last people who touched it, we will get blamed.
2. Automatic transmissions run on unfathomable witchcraft, and must never be disturbed lest ye anger the gods.
Seriously, it is rare to find someone who understands how automatic transmissions work, even (or especially) in trans shops.
If they seriously believe that the only thing holding your trans together is dirt and varnish, how can they even let you leave ?

This idea that engine oil must be changed religiously every fifteen minutes - the more the better - while trans and differential products are good until the zombie apocalype, is hilarious.
You are on the right track IMO.
 
Originally Posted By: milkboy

The caps weren't directed at you, they were directed at your mechanics. Let me over-simplify further - go somewhere else.
wink.gif


Transmission shops have a tradition of recommending against fluid changes on old and / or high mileage units based on two ideas :
1. It is ready to break, and if we are the last people who touched it, we will get blamed.
2. Automatic transmissions run on unfathomable witchcraft, and must never be disturbed lest ye anger the gods.
Seriously, it is rare to find someone who understands how automatic transmissions work, even (or especially) in trans shops.
If they seriously believe that the only thing holding your trans together is dirt and varnish, how can they even let you leave ?

This idea that engine oil must be changed religiously every fifteen minutes - the more the better - while trans and differential products are good until the zombie apocalype, is hilarious.
You are on the right track IMO.


No worries, thank you for clearing that up.

You are mostly right:

The 2 mechanics that gave the advice not to change fluid were not going to be hired to do the job.

The first mechanic is a guy that moved his shop to Florida, I called him up here in NY to ask his advice.

The second mechanic was the Previous Owner's guy who he(the PO) mentioned while doing an oil change that he was going to drop the pan himself at home. His mech. then advised him to leave it alone.

But, I do agree with you, hence why Im changing the old stuff out.

I want to share with you something that happened to me when I was looking for a car 7 years ago and why I'm kinda spooked about this whole subject:

Quote:
I remember once I was looking to buy a '92 Ciera and the PO claimed he just did a trans. service (not sure of flush or just pan drop) as part of his hard sell. But when I took it for a drive, it didn't want to get out of first and when it finally did, it kicked really hard!

That sticks in my head real good and makes me nervous to this day. The truth is, he probably had the problem before the service was done and thought the new fluid and filter would fix it, but in reality the damage was done. I can't say for sure, but I surmise that's what happened.
 
I stopped borrowing my father's car when I was seventeen because if I drove it ten miles, I would be blamed for anything that went wrong with it in the next two months.
 
Originally Posted By: milkboy
I stopped borrowing my father's car when I was seventeen because if I drove it ten miles, I would be blamed for anything that went wrong with it in the next two months.

I know exactly what you mean, lol
 
I'm posting a little late here but just to add an anecdote, I have a 1986 THM-125C (aka 3T40), which originally called for Dexron II. I take it to be the little brother of your trans.

When I bought the car I did a filter and a couple fluid changes with Castrol Dex/Merc, same as you've been using. I have no idea if it's the best choice, but nothing noticeable has happened to it. It still shifts as firmly as it did with the PO's fluid, whatever it was. It's actually more firm than any of the other 3T40s I've owned or driven. I interpret that as a mechanical difference between variants of the transmission, but maybe it's fluid or the condition, who knows.

The Castrol has been in there for 2 years now with rare topoffs of the same fluid. The only time I've had a slight slip was when I let the fluid get low AND it was still cold. With fluid at the correct level it's held perfect and shifts solidly under all conditions.
The TCC lockup pulses when trying to engage sometimes, but it already did that before the fluid change. Actually I think it's better than it was.
 
Originally Posted By: armos
I'm posting a little late here but just to add an anecdote, I have a 1986 THM-125C (aka 3T40), which originally called for Dexron II. I take it to be the little brother of your trans.

When I bought the car I did a filter and a couple fluid changes with Castrol Dex/Merc, same as you've been using. I have no idea if it's the best choice, but nothing noticeable has happened to it. It still shifts as firmly as it did with the PO's fluid, whatever it was. It's actually more firm than any of the other 3T40s I've owned or driven. I interpret that as a mechanical difference between variants of the transmission, but maybe it's fluid or the condition, who knows.

The Castrol has been in there for 2 years now with rare topoffs of the same fluid. The only time I've had a slight slip was when I let the fluid get low AND it was still cold. With fluid at the correct level it's held perfect and shifts solidly under all conditions.
The TCC lockup pulses when trying to engage sometimes, but it already did that before the fluid change. Actually I think it's better than it was.

Thanx for the reply, it's never too late to add to a thread, especially if it's useful info!

The slight slip you refer to... is this something that only happened after the Castrol was in there, or was it something that was always an issue?
 
I am pretty laissez faire about automatic transmissions. Generally, though, a little slip when taking off cold is due to being a pint low. I once cured a slipping torque flight by dropping the pan , replacing the filter and whatever ATF that drained out. The BMWs have drains. On one, It has had a lip seal fail and then a line break so the fluid has been changed 3 times since I base lined it in '06 drained. The other had its entire capacity drained during extensive body work.
 
ANY slip in an autobox is bad news. Especially when cold. Just like your engine the slushbox has its highest pressures when cold, even though many now carefully regulate the internal pressures.

In my car it is a common complaint to hear folks cry about cold slippage, it's really your trans crying out for some fluid!
 
Originally Posted By: exranger06
Changing fluid does NOT kill transmissions. Even if it was a high mileage unit, I would change all that fluid out and not worry about trans problems. On a low mileage unit, it's a no-brainer. Change it.


+1 change it.
 
Originally Posted By: Donald
Originally Posted By: hardcore302
I'm convinced that half the cars in this country have the factory fill in there until they die at 200K..



Maybe, but the other half have the factory fill when they are towed into a transmission shop for a rebuilt transmission.


There is such a thing as preventive maintenance.
 
Originally Posted By: babyivan

The slight slip you refer to... is this something that only happened after the Castrol was in there, or was it something that was always an issue?


I don't have any memory of it happening, but I also didn't create the same scenario with the old fluid. We weren't into the cold months yet, and according to my notes the level was slightly overfull at the time, not low.
He left 2 empty quarts of trans fluid in the trunk, so I know he was topping it off. That seems like a lot, so maybe it was leaking more quickly for him before I changed the pan gasket. He also lived in a flat area so he might have gotten away with lower levels before noticing the leak.
The empties were blue bottles, I don't remember the brand, I'm guessing NAPA or Super Tech. So it was at least partially, if not entirely, non-original fluid.

I did the fluid change pretty quickly after buying the car, so I didn't get much experience with the old fluid.

The exact scenario when I had it slip is really these 3 conditions combined
1) fluid is low (my fault)
2) I've just started driving the car, transmission cold
3) I stop at a sign, turn and lightly accelerate up a fairly steep hill.
If all 3 of these conditions occur at once, then it would slip for a second during the 1-2 shift on that hill.
That was it - for any subsequent stops and starts, any hill, part or full throttle, never any issues even though the fluid was low.
I never had the same low fluid scenario on the PO's fluid so I can't compare how they handled it.

I just blame this on myself letting the fluid get low. Once I topped it up it stopped doing that. Even though the gasket was replaced the transmission still seems to have a very slow leak, slow enough that I forgot all about it until several months later it acted like described above.

I can't find any fault with the Castrol. To put my positive spin on it - it works well enough that even when it's a pint low, it still won't slip unless I drive it uphill while cold.
smile.gif
 
Originally Posted By: SteveSRT8
ANY slip in an autobox is bad news. Especially when cold. Just like your engine the slushbox has its highest pressures when cold, even though many now carefully regulate the internal pressures.

What I've experienced with old cars is that if they slip at all, it happens when cold. If they slip when warm they're long gone or WAY low on fluid.


Quote:
In my car it is a common complaint to hear folks cry about cold slippage, it's really your trans crying out for some fluid!
Agreed, it's something to promptly address as the slipping equals wear to the clutch pack that can't be undone.
What kills me are the people who don't realize what's happening, and floor the throttle as it slips.
 
Im at the trans shop now doing a pan drop/filter change.
I will be replacing the lost fluid with Castrol dex/merc.

Good news is, the mechanic tells me that it's been done before on my car.

Fluid looked good, no metal in the pan!
 
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