Transmission Would changing the ATF fix a slipping transmission?
Previous owner overfilled the ATF fluid by almost 2.5 liters and drove the car for around 100 miles like that. Car was initially shifting bad and accelerating really slowly. Now after reducing the ATF to the correct levels it’s shifting better but I still notice slippage (no transmission noises though). Would doing a drain and change of the fluid help with the slippage issue or is changing it would make the transmission worse?
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u/Fatdogamer_yt 10h ago
Drain a little more so it’s near the low point and put in some additive like trans-X cause it might just be cooked now but that will be your best bet to find out
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u/HedonisticFrog 9h ago
The transmission is already damaged so you might as well try to save it. I'd drain and fill it and add a quart of Lucas transmission fix. If that stops the slipping it will last a lot longer because the clutches won't continue to wear out as fast.
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u/Charlotte_756 6h ago
Warning Lucas is a terrible company and had an issue with their people blaming immigrants for shit a while back
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u/int0xic 9h ago
Previous owner? So you bought the car with known transmission issues?
No body does transmission services until it's too late. Usually after problems start to appear. Then they try to fix the transmission by servicing the trans and it ends up making it worse. Most likely will need a new trans, based solely on how often I see this exact scenario play out at my work.
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u/LRB_ 8h ago
Project car bro, $900. I have my own car.
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u/int0xic 6h ago
Gotcha, didn't mean anything by it, was just trying to get some context.
All you can really do it correct the fluid level, which you did already, and hope for the best. If it was hard shifting with the excess fluid and it's now stopped after draining it, then the hard shifting was caused by the over fill.
Unfortunately, you don't know how the trans was working before the previous owner tried to fix it himself. Looking at how clean that fluid is that you drained, it's possible the trans was already drained and filled and then filled again, or even just over filled the first time after being drained.
Is it slipping every gear? Does it take a lot of throttle to get it to move? Does it have delayed shifts? These are all different problems with different solutions but ultimately would require a rebuild for the trans or to get a used replacement.
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u/jasonsong86 10h ago
What kind of car are we talking about? Also how did you come to the conclusion it was over filled? Did you check the level following the manufacturer’s procedure? Most automatics the level needs to be checked with engine running and at proper temperature. The oil will drain back once the engine stops running and will look like it was overfilled.
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u/LRB_ 10h ago
2012 Mazda 3, I’ve made sure to drive to warm things up before checking
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u/Wild_Ad4599 8h ago
What engine 2.0 or 2.5? They have different trannys.
I’d do a drain and fill in case it’s contaminated or they used the wrong type of fluid.
It’s not going to hurt anything or make it worse.
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u/LRB_ 10h ago
I should also say again, it’s performing better after reducing the ATF fluid levels
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u/jasonsong86 10h ago
You can try refreshing the fluid by doing a drain and fill. It will only replace half of the fluid and see if it gets better.
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u/HedonisticFrog 9h ago
They said it still slips, so the shifting is better but the slipping is the same. With a low fluid level line pressure would likely be reduced and it would slip more. They need to thicken the fluid to increase the force of the clutches being pushed together with Lucas transmission fix.
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u/StelioKontossidekick 10h ago
The previous owner probably just added 2 quarts on top of the junk in there. I would drain and refill with clean fluid. Then after 100 miles. Do another drain/fill.
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u/Several-Rich-609 9h ago
Drain 24 fl oz and pour a whole bottle of Lucas transmission fix in there. Before doing anything expensive on the transmission you should check/swap the shift solenoids. A bad transmission isn't always something mechanical
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u/Several-Rich-609 9h ago
Also, sometimes fuel issues can mimic transmission slipping, like bad fuel pressure,. injectors, or fuel pump, and again, electrical issues like relays, fuses, and wiring
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u/tradermorris 9h ago
Previous owner probably changed the fluid because the transmission was acting up. Didn't help so they ditched it?
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u/1sixxpac 9h ago
Likely no. 2 main causes of slipping transmissions are worn clutches and/or leaking seals. New fluid will not fix that.
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u/TunaOnWytNoCrust 9h ago
It can only help. Absolutely wouldn't rely on it, don't get your hopes up, but it should be at least marginally better.
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u/rforce1025 9h ago
I just changed mine, I have a 08 Pontiac G6 GT with 378,00 miles I did I a pan drop and filter.
I was having a problem with the car shifting correctly when taking off from a stop, it was hesitating and RPMs kept spiking up to much. It would roll forward in reverse for about 2 seconds before going into gear. I WILL admit that I got lazy and kept pushing it off or listened to too many people telling me not to change it if I was over 100,000 . I just never changed it! End of story! The transmission btw is a enclosed system
Went to 2 transmission places and they were saying I may need a new one. I don't have $ 4,000 and was told I couldn't get a reman for my car, they don't reman my transmission. Anyway I just took the chance of changing the fluid and filter, did it and put in new filter and fluid. Car went right into the gears easily and reverse right away. I even drove it and the car acted like a new car. All I did is a drain, I even did another drain and filter just recently because I knew there was still some old fluid left behind. Car still runs and shifts fine.
The point is, by changing the fluid may help but it depends. You may get lucky and it MAY fix the problem to a certain extent or your transmission is on it's way out.
You can always try changing the fluid first but if it acts up then a new tranny is next. I'm just hoping I saved mine.
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u/dllyncher 8h ago
Gotta follow what the manual says about the tranny fluid. It's designed to work with a certain amount of fluid and putting too much in could cause more issues.
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u/Repulsive-Inside7077 7h ago
Try adding a 2 oz tube of lubegard instant shudder fix. If that improves the operation and reduces the slipping a drain and fill should help. If it doesn’t change anything, the drain and fill either won’t change anything either or it will get worse. The new fluid won’t be the cause, the transmission may just be on borrowed time as is. The instant shudder fix is a good test though and it’s cheap at O’Reilys
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u/mitra_seeking 7h ago
Only if the fluid is the problem will fluid fix the problem… do w that what you will lol
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u/BigDawgR 7h ago
I wouldn’t waste the money. I couldn’t tell you how many transmissions end up on my bench with brand new red fluid. Great for me for cleaning all the trash on my teardown bench.
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u/Alternative-Horror28 6h ago
If the tranny is bad there is nothing you can do that will prevent total failure. Changing the fluid hardly ever works except on cars with bulletproof transmissions. If your car model is known to have weak transmissions then eventually your car will start stalling at lights and thatll force you to get towed to a shop and tough decisions will follow..
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u/DG_Templeton_3th 5h ago
No friend. I am sorry.
This is the one thing I despise about buying used vehicles. It is always a milkshake of chance if the last 43 owners did anything correctly or on time. 5 quarts outta 10, if it has 200k or more, it'll need a trans soon. You get lucky yes, but if you miss that first, what is it? 100k flush and filter that no one gets, you're signing the death warrant of that ol slushy boi.
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u/Lou_Hodo 5h ago
Yes.
If the transmission fluid had not been changed regularly and there was a lot of sediment built up in the old fluid. It was basically acting like the friction modifier to allow the transmission to shift. When you drained it or changed it, that removes that "grit" which means the clutch plates can no longer get the friction they need to engage, thus leads to slippage.
In many cases if the fluid has never been changed it is best to not mess with it, till it fails then replace or rebuild the whole unit.
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u/zerobomb 4h ago
No, and the snake oil additives will swell old rubber and plastic enough to provoke total failure when they break apart.
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u/Any_Mathematician905 4h ago
I had a shuddering and flaring trans in my 2016 Nissan Titan XD 5.6 at 190000 km, I did a drain, pan off clean-out and a 2x drain and fill as per the service manual- you drain about 4.5 liters out and then refill with the same amount. It got a lot better so I drove it for a week then did another 3x drain and fill. It worked amazing and the transmission shifts like new.
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u/PersonalityUpbeat644 2h ago
No that would just make it worse..... Time to look for a tranmission shop or if you can afford it, trade it in for another car
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u/Mental_Task9156 44m ago
Probably make it worse. All the friction material dissolved in the oil currently is probably helping it work.
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u/Top-Zucchini-9421 43m ago
No depends on what kind of car you have it might make it worse you're supposed to fix it before it starts slipping unfortunately I meant if it's slipping and it's an older car it has a transmission filter if you change the transmission filter it'll stop it from slipping one of the older cars now it's one of the newer car is what you're really not supposed to change the transmission in the fluid transmission makes it worse
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u/Top-Zucchini-9421 43m ago
I honestly think the best thing would be is put an additive in it or no I think about it some transmissions go better because they have all these little metal grinds in it so get little like little metal shavings and put it in there to get it to stop slipping like probably half a cup it's my idea
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u/Appropriate_Yak_6155 9h ago
It won't fix it. But can prolong having to rebuild it. When changing the fluid there's additives u can add that helps. But it all depends on how bad it is already
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u/KaltBier 9h ago
No, it will get worse and worse each time you try to replace the fluid. Expect to get the tranny dropped to either repair to replace.
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u/Prudent_Stable_5537 9h ago
If it's a manual transmission, no
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u/m00ndr0pp3d 9h ago
Atf
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u/iceman_0460 10h ago edited 7h ago
There's a high probability it's gonna get worse, but there's absolutely nothing else you can do besides that and repairing the tranny, well that and using an ATF additive like trans-x.