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Automatic Transmission question.

FatstratFatstrat Member Posts: 9,147
edited May 2009 in General Discussion
I bought a vehicle w/200K miles on it. Planned on dropping the tranny pan, draining old fluid and replacing filter.
Co-worker says bad idea. He once did that to a good running high milage vehicle, and tranny began slipping within days. Attributes it to the detergents in the new tranny fluid.
What say you? Change or leave as is?
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Comments

  • FatstratFatstrat Member Posts: 9,147
    edited November -1
    A few weeks back I siphoned most of the fluid out of my 93 F-150's tranny. Replaced w/clean fluid and some Slick 50 tranny juice. Drove until hot as per op instructions & checked. Adjusted until it checked perfect. Level exactly on full line.
    Now when I check it, it checks overfull. How can a tranny gain fluid?
    Could it be that the Slick 50 stuff, which is thick going in, gets thin and gains in fluid mass?
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  • Sig220_Ruger77Sig220_Ruger77 Member Posts: 12,748 ✭✭✭
    edited November -1
    Might as well change it. If is starts slipping because you changed it, it was only a matter of time before it would have went bad if you hadn't changed it IMO.

    Jon
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  • mango tangomango tango Member Posts: 3,833 ✭✭
    edited November -1
    Do one of those fluid transfusions, they work good!
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  • btkbtk Member Posts: 2,298 ✭✭✭✭✭
    edited November -1
    I've been told this also. I asked around and a guy I trust told me if the tranyy has not been serviced like it should, then don't do it. If the trany has been serviced regularly then it won't be a problem. If you don't know thw service history you're taken some chance of it going down hill afterwards.
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  • jonkjonk Member Posts: 10,121
    edited November -1
    I've heard this theory before and I think it is spread by transmission repair shops. How can changing a lubricant to make it do it's job better mess something up?

    I have a 93 Tempo and I've changed the fluid like clockwork every 40,000 miles. Still works fine. The car is about to rust out and blow away in the wind but the engine and tranny are fine. (Knock on wood)
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  • mogley98mogley98 Member Posts: 18,291 ✭✭✭✭
    edited November -1
    I don't know if a test has ever been done to prove it but I have always heard that if you fail to maintain gunk builds up and acts like bearings and seals, when you clean and rinse so to speak you wash out the "sealer and bearing material" so to speak provided by the gunk, if you have always maintained the system then these deposits have not accumulated and should not be an issue. I have always heard this but can not prove it.

    On the other hand when I had my boat engine rebuilt the guy showed me two engines in his shop, one was run with any gas, and any oil mix, the other was run only with 93 octane and TC3? I think high grade oil, if it was not a set-up clearly the engine run with higher test gas and oil had no deposits and a nice swirl at the top of the piston, teh other engine was a mess. Still since I don't know the circumstances and don't know all the facts I would say it could have been a farce. Would like to see quality data on it actually.
    quote:Originally posted by jonk
    I've heard this theory before and I think it is spread by transmission repair shops. How can changing a lubricant to make it do it's job better mess something up?

    I have a 93 Tempo and I've changed the fluid like clockwork every 40,000 miles. Still works fine. The car is about to rust out and blow away in the wind but the engine and tranny are fine. (Knock on wood)
    Why don't we go to school and work on the weekends and take the week off!
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  • NOSLEEPNOSLEEP Member Posts: 4,526
    edited November -1
    Automatic transmissions primarily fail because of heat. Add a can of automatic transmission conditioner. Drive it for a week or two, the
    seals will soften up and add extra life to rubber seals in the clutch
    packs. Change the transmission fluid if it is old or turning from red to a darker color or smells like it is burnt. If the oil is already burnt you are just just running her on borrowed time.
    The seals fail and let the clutch packs slip when they get hard from
    getting to hot. The conditioner allows the seals to soften and expand.
    sealing the clutch packs in forward and reverse gears.
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  • 47studebaker47studebaker Member Posts: 2,251 ✭✭✭✭✭
    edited November -1
    had a 96 chev K1500 the trans was slipping once in a while, had it flushed and added a can of Sea-foam Trans cleaner. No further problems. Took a long trip in the wifes 99 Continental and it started to leak/blow trans fluid from under it. Took it to a trans shop, couldn't find the leak and fluid was OK. Did a flush and can of Sea-foam. Still have the car and now has 30,000+ more miles, no problems. I'll try a $100 stab in the dark before a $1400 trans rebuild.
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  • Colt SuperColt Super Member Posts: 31,007 ✭
    edited November -1
    Most of the scientific data on this and similar subjects can be found

    at www.sae.com

    Society of Automotive Engineers.

    Doug
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  • BlairweescotBlairweescot Member Posts: 2,014 ✭✭✭✭✭
    edited November -1
    "A co-worker" did a tranny fluid job once, and it slipped within ten days...so don't ever change that fluid if nothing is wrong

    That is the same logic Wile E. Coyote used [:)]

    Ever stop to think that co-worker might be a ham-handed F who is a lousy mechanic and shouldn't have tried to do it in the first place?
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  • penetraitorpenetraitor Member Posts: 3,870
    edited November -1
    If its been to long I wouldn't change it. Just drive it until its done. When you change it your removing the old clutch fibers that are now in the old fluid. This acts like a grit to keep them from slipping.
    I'd find out history and go from there.
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  • tomahawktomahawk Member Posts: 11,826
    edited November -1
    change it and add lucas transmission additive.. most failures are due to dirty filters causing the transmission to overheat..i work on them all the time...if its clean there is less chance of a piece of metal getting hung up in the valve body[;)]
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  • catpealer111catpealer111 Member Posts: 10,695
    edited November -1
    The problem comes from changing the fluid on on high millage trans when the fluid has never been changed before. All of the clutch material that's worn off is still in suspension on the old fluid allowing everything to keep working. Once you drain out that original fluid and replace it with fresh, you loose all of that "grit" that was allowing the old, worn clutches to work. I have seen people do this and I've done it myself before I knew better. If you don't know if it's ever been changed and it's not burnt, just top it off and keep driving the car as is.
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  • JamesQuinnJamesQuinn Member Posts: 123 ✭✭✭
    edited November -1
    I know it's a weird idea, but why don't you try following the manufacturers recommendation? Some say flush every 60K, some never.

    I have a Volvo with a BW which says flush every 60K. I do that. I have a Caddy with a GM which says never flush. I follow that reco too.

    Do you even know what brand tranny is in your vehicle?
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  • SuspensionSuspension Member Posts: 4,783
    edited November -1
    I would change it without a second thought. I've done it many times in the past without a problem.
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  • haroldchrismeyerharoldchrismeyer Member Posts: 2,213 ✭
    edited November -1
    If the fluid isn't dark, drop the pan, change the filter, and refill. If it is real dark, remove a cooler line first, put a rubber hose on both ends and place in a five gallon bucket. Open 12 quarts, and start the vehicle. Pour fluid in about as fast as you can, and it is going to be coming out of the cooler line. After 12 quarts,shut it off, pull the pan, change the filter, and refill.
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  • dheffleydheffley Member Posts: 25,000 ✭
    edited November -1
    If it's been changed regularly, change it. If not, don't. Pull the dipstick, if it's cherry red and has no burnt smell, it's probably fine to service. If it's dark or smells of any burn, run it until it fails and rebuild it.
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