Sorry but I can't agree. There is nothing good about old oil. It is contaminated and contains a small percentage of it's original oiling capabilities. It will shurly lead to the demise of the tranny. The rest of the trans needs good oil also (mainly the bushings). There are a lot of tales about auto trans because they are expensive to fix and people dream up remedies for it. The band and clutch material is hard enough so there's nothing to "wash away". You can take a driven clutch disc out of a clutch pack on an old tranny and clean it up in solvent and it will look exactly the same. It's not like it is leather or something that absorbs contaminants to the point where it gets denser.
Ok, if I have a trans that is slipping and change the fluid nothing will change - for better or worse?
They usually slip due to lack of pressure from the front pump and not clutch wear. If it is slipping it will not last long anyway. It depends on the tranny and exactly what is wrong with it so I won't venture to answer that question but I whould at least change the pan oil if it was mine. Old oil should give more friction at the plates but less pressure from the pump.When I was a mechanic (long time ago) they used to just fix whatever was worn and charged much less but I know know if they still do that. It's like a disease; the earlier you fix it the less it will cost you. Sometimes it is just a pump and seal and maybe a few friction clutches. (And o-ring seal kit)
In my opinion there is NEVER a detriment to changing the trans fluid. If the trans isn't damaged it will help it. If it is damaged it won't fix it, but it won't kill it, either. It may already be dead when the new fluid is installed, and finish dying afterwards, but I do not believe that new fluid will harm ANY transmission.
__________________ Mark
Former Ford automatic transmission engineer, 1988-2007.
In my opinion there is NEVER a detriment to changing the trans fluid. If the trans isn't damaged it will help it. If it is damaged it won't fix it, but it won't kill it, either. It may already be dead when the new fluid is installed, and finish dying afterwards, but I do not believe that new fluid will harm ANY transmission.
As the transmission ages, the friction material on the clutch disc packs and bands wears and becomes suspended in the fluid. This seeming is all ok, until you drain the old fluid and put new in. New ATF very high cleansing properties (every get new ATF on your hands, it's pretty clean stuff) and proceeds to "wash away" much more of the remaining friction material from the clutches than the old fluid would, hence the trans fails.....as long as you have regularly changed your trans fluid (every 20-30k or so) that you can continue doing it and the trans life will benefit.
That's failed logic.
If new tranny fluid "washes away" the friction material, then changing the tranny fluid "every 20 - 30k" will cause the friction material to wash away FASTER, causing the tranny to fail quicker.
Stewart
__________________ The Brotherhood of FTE <~click the link 1999 F150 Lightning: WMS built block, 6lb lower, Monsterbox, Truetrac, CF driveshaft 2002 PSD F250 SC 4x2: 38R, AC codes, MBRP 4", AFE, JWVB, Riffraff HPX, CCV, and boots, ITP OBA, Live Tuned by Jody 2000 PSD Excursion 4x4: John Wood 4R100, F5, MBRP 4", AFE, BDP 1.0, ITP OBA and Pre-Pump mod, V & B code springs, Hellwig rear sway
Don't forget. The same mechanic that tells you not to change you tranny fluid "until it acts up". Is usually the same mechanic you go to when your tranny "is acting up" and they tell you "you need a new transmission". Hmmmm???? Makes you wonder where their coming from. Lets say you have 150,000 miles and you never changed the fluid and you have to replace / rebuild the tranny. Lets say a 30K service is $200. You would have spent $1000 for maint. For a rebuild you'll spend $3000 - $4000. Hmmmmmm???? Now which service would your mechanic rather do? Any mechanic that tells you not to change the fluid at regular intervals is an idiot!
I think 99% of the old tales (like don't change your oil) comes from people that have never had a transmission apart (and probably don't own a wrench) and they come up with this stuff because they are grasping for a remedy thay will prolong their expensive repairs and unfortunately other people that are in the same boat believe them..........no offense RLH (op)
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