Here’s Why Changing Your Transmission Fluid Can Cause Damage

Here’s Why Changing Your Transmission Fluid Can Cause Damage


rev up your engines, today I’m going to help
you answer the question, can changing your transmission fluid cause damage to
the transmission, now people are always asking me, Scotty some guys tell me
don’t change the fluid my transmission that it may start slipping or stop
shifting gears right, is that true or not of course you don’t want to damage your
car by not maintaining it, but on the other hand, you don’t want to maintain
your car and then damage it through the maintenance you’re doing, so here’s the
truth, a little history helps explain it General Motors made the first really
commercially viable automatic transmission using hydraulic fluid to
drive the transmission, instead of using a manual clutch, where the clutch is
clamped down to the engine and when you step on the clutch it releases it, so you
can shift gears and when you pick up on the clutch it goes back down so the
engine and the transmission are mechanically connected, an automatic
transmission uses what’s called a torque converter, there’s fluid inside and even
though the torque converter is bolted to the flywheel on the engine is
mechanically connected, the connection between the torque converter and the
transmission is using fluid dynamics to make it go, it’s not physically connected
and they have to make them that way for one reason, when you come to a stop in a
standard transmission, you have to push down on the clutch or put it in neutral,
or the car will stall out, but with an automatic, that doesn’t occur, while
you’re sitting there, the torque converter just has complete slippage and
so the car doesn’t stall out from the engine being jammed against a piece that
isn’t moving anymore, here’s a torque converter taken apart, you can see
there’s all kinds of little crevices and friction plates, the fluid allows the
mechanical spinning of the engine to be transferred to the transmission using
fluid pressure and fluid friction, now because this transfer is done in very
small spaces, it requires a very thin clean fluid, if it was thick it would
just jam the whole system up and not work right, and believe it or not the
early automatic transmissions some of them used whale oil, talk about save
the whales, we were killing the whales to drive our cars, so
guess what you need clean fluid in your transmission or it won’t work right now,
years ago when I was a young mechanic, we changed the fluid and filter in
automatic transmissions every twenty or thirty thousand miles to keep them
running smooth, but today modern fluids have a higher quality as do some of the
transmission parts, some of them use fully synthetic fluid, you still do need
to change it though regardless of what anybody’s going to tell you, if you want
your vehicle to last for hundreds of thousands of trouble-free driving, now
the fluid in the Celica has been changed every 40,50 thousand miles I’ve changed
it and it’s got 240 thousand miles on it still has the original transmission and it
shifts like a dream, but if you have not maintained a transmission correctly and
now say you got a car that’s got 150 thousand miles on it, the fluids all
black and you think, gee I’m going to change it, well guess what that may not be a
good idea, because if you have a really dirty transmission, your torque converter
is working with dirty fluid, dirty fluid has more friction, that may be the only
thing that’s still making it drive down the road and not slip, you change out
that really dirty fluid, hey I’ve seen many people do that and what happens is
they slip or they don’t even move on their own, that you’re really better to
leave alone if the transmission is still working, you’re living on borrowed time
then anyway, or you might try some of this Lucas transmission slip fix, which
works like this, if you have a high mileage car, with really dirty automatic
transmissions, you can get a bottle of this Lucas transmission slip stop, it’s
24 ounces, you drain 24 ounces of fluid out of the transmission and only
24, and then you add that into the automatic transmission, sometimes that
can keep it from slipping, the ones that have already started slipping, and if you
have really dirty fluid it can at least protect it for a while longer, realize
that automatic transmissions hold a lot of fluid, some of them hold 14,15 quarts
of oil, so if you just drain out 24 ounces, and put in 24 ounces of this,
you’re not radically changing the consistency of the fluid like you would
if you drained it out and put all clean fluid in a dirty transmission and then found out, oh my god it’s slipping now what am I going to do, but of
course you’re better off changing the fluid regularly in the first place, not
getting into such a mess, and I know some people are going to say, Oh Scotty those
new cars say it’s lifetime fluid, you never need to change it well, if you’re
going to keep your car as long as possible that’s a bunch of nonsense, it still
needs to be changed I talked to my transmission man about
that and he says, Scotty you should see some of these cars, we advise them even
though it says lifetime, change it every 50,60 thousand miles
even with synthetic fluid, because we’ve seen the ones that have a hundred
thousand miles 120 and they break and when we take them apart,
there’s nothing but crud inside from it breaking down, he told me that he’s seen
tons of Nissan’s that if they will only change the fluid every 50-60,000
miles even though it said it’s a lifetime fluid, that he wouldn’t have had
to rebuild those things so soon and spend four or five, six thousand dollars
on a job that, hey if you change the fluid and paid a guy like him 100
something dollars to do it, you wouldn’t be in that mess in the first place,
regular maintenance is the key here, like I said, if you wait too long and it’s too
dirty, with too many high miles on the car, if you do change the fluid, a lot of
times the transmission will go out entirely,
and then you’re going to have to spend a ton of money fixing it, because this
Lucas stop slip, hey it’s basically just a band-aid, it might get you a little
more time out of a transmission that’s really dirty and isn’t working right, but
it’s not a miracle it’s not going to rebuild your transmission because it was
all ruined from dirty fluid, and to give you one more warning, people always
asking me about transmission flushes, my advice never flush out an automatic
transmission, too much damage can be done by pushing dirt into small crevices, when
you change it, you drop the pan, you change the fluid, and the filter if it
has a filter, and leave it at that, the flush machines they can cause more
damage than good that they might do, so now you know the truth about automatic
transmission fluid changing, and if you follow my advice, and buy the right car, you
can have many miles of trouble-free shifting in your car, because
some cars they just have poorly manufactured automatic transmissions, and
it doesn’t matter what you do to them they’re going to fall apart well before a
hundred thousand miles anyway, but if you do pick the right manufacturer, you can
get this kind of mileage out of a transmission and even more, so if you
never want to miss another one of my new car repair videos, remember to ring that
Bell!

About the Author: Michael Flood

100 Comments

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  2. Scotty , I have a 92 Chevy pickup. I think it’s the 700r4 since it has a tv cable. It has 170,000 miles. When cold it shifts firm and positive like it should but when it warms up you can’t feel it shift . Two questions- what’s the most likely problem #2 with 170,000 on the truck what is the likelihood it’s the original trans?

  3. Then there's the people who get cars from previous owners who never changed the transmission oil, and you have to deal with their negligence.

  4. I change oil every 3 to 5 whenever I have time. All other fluids i do every summer. My car is newer and for the 200-250 it costs me to change myself it's worth it just for the piece of mind. 4x drain and fill in tranny to get as much of the old fluid out. Honda pilot some of them already failing from 2016 and up!

  5. I have a 2016 Hyundai Elantra with 140k miles on it. Every time I got my oil change they would skip the transmission levels. Long story short I have never changed the trans oil. What is my best option? Leave it? My car has a sealed transmission. Can’t change the filter either because it’s inside the tranny. What should I do? Please reply thanks and God bless

  6. The biggest PITA i'm finding after buying a nissan is that since 2014, they haven't even been including transmission dipsticks.

  7. Changing the transmission fluid will NOT damage the transmission. Not changing the fluid or doing incorrectly WILL damage your transmission.
    If you change your fluid and it dont work afterwards, you did something wrong or it was broke before you fucked with it.

  8. I was told by Toyota not to change my fluid, i got over 205k on my 2005 4runner and not one issue with the tranny.

  9. Hey Scotty!
    Can you change it too often? (Error on the side of caution if I forgot when I did it last or just being extra proactive). 2011 Accord EX-L V6.

  10. I got 2006 Toyota Corolla 135,000 , bought with 55k was wrecked and had a rebuilt title. I have not changed the transmission oil. So it seems like a gamble either way whether to change it. Thoughts anyone?

  11. Can i change the transmission filter and fluid that was in pan only. Of transmission fluid is brown i dont wamt to flush just fluid change

  12. So my 07 pt cruiser ran really low about 2 months ago and noticed I had a lack of passing acceleration. added a full quart and have been driving still, took it to a local shop, mechanic took it for a drive and says it slips in 3rd, you need a new transmission. It works fine with normal, easy acceleration but punch it and you go nowhere. I took the pan off, new filter, fluid and some of the Lucas oil shown in video, we'll see what happens.

  13. Can someone explain why a flush may damage a transmission? I've been wanting to get a flush on my 09 Toyota Rav4 transmission with only 53k miles, but everyone keeps advising not to. If it flushes out all the old fluid, the pan is dropped, cleaned, a new filter is put in, closed up and filled with new fluid, I just don't understand where that would damage my transmission :/

    Thanks!

  14. Old man is crazy telling people not to change dirty oil lol. He obviously wants cars to break down so he can pretend to fix them

  15. I'm still confused. If u flush it the oil will be changed too….its essentially the same thing…except if u change the filter and gasket….

  16. Or do what I did , a partial fluid change ! What does that mean ? When you drain your trans fluid ,only about  1/2  or less will come out , plug it back , refill the other 1/2 or what ever came out , and be careful on measuring what came out and what you put back in. Drive for another 4-6 thousandmiles , and simply repeat the process , once more and you are good. Flushing all fluid on a vehicle with 70-80K or more may end up in disaster.

  17. I changed the transmission filter, fluid, and transmission pan on my '95 Ford F-150. The truck had 134,000 miles on the original transmission fluid. The old fluid looked brown. The new pan has a drain plug so I can do drain and refills without removing the pan. The truck runs great and the transmission shifts like it always did, no slippage. I'll do two more drain and refills to get most of the old fluid out. Thanks for your videos.

  18. My wife's Trooper (Chevy tranny of course) got so bad I had to tow her home from town twice. I drained and changed everything and it has worked great for years now. (Syn fluid) Slight slippage in one "gear" but nearly never happens. I've had the Lucas for a couple years and one of these days…..but that band is adjustable as well so I will do that at next change and soon as well, lol. Thanks Scotty. Big fan here

  19. I just seen this I had 2 change a spring under my trans pan on 97 dodge ram 1500
    And now it wont shift in2 5th gear
    Well at 90mph and 4k rpms later it finally shifts in2 5th gear
    But since I was in there I changed the filter and it's still bad what is going on

  20. SCOTTY I HAVE A QUESTION.i HAVE A FORD EXPLORER 2003 WITH 130,OOO MILES,SHOULD I REPLACE THE FLUID?

  21. I wish I saw this 2 weeks ago. Sport City Toyota in Dallas maintained our 2010 Sienna minivan since we bought it there at 7K miles. They recommend transmission flush at 100K miles and they did it at 112K miles. Picked up the van from service and drove it out of town 2 days later when transmission gave out on highway. $5,700 repair estimates. All places I spoke to said we should never have done the transmission fluid flush given high mileage but Sport City says they do it daily with no problems.

  22. A basic drain and fill should not hurt anything. It's when you drain the ENTIRE system that problems come up. You are not supposed to do the entire system on any car anyways, as what's deep inside the torque converter should always stay there.

  23. Thanks for the good info! I fell into the trap of lifetime. Now I have 3 rd gear slipping in my Corolla. Was going to drain the tranny and change filter but after your video I am probably just going to go with the Lucas option for now. Thanks again! First time viewer here.

  24. How can I tell if the fluid of my transmission have ever been change? I had bought a chevy traverse with over 140k miles, it runs perfect but I want to be ahead of any problems…

  25. So I bought a Volkswagen Passat Wagon v6 2.8 with shifting delays in first gear automatic. Could changing the transmission filter be a risk? I've watched a previous video from Scotty which indicted a change of the trany filter can help. Thank you please give me a feedback.. 🙏

  26. I'm of the opinion that clean fluid is always better than dirty fluid. I neglected my dodge avenger and didn't even touch the tranny til 145k miles. The owners manual says to change the fluid at 140k miles, Mopar aft +4 is ultra premium synthetic so it was alright, just dirty. I've since replaced all the fluid and filter, its red and clean and the tranny did not fail , its very happy and shifting like a dream.

  27. Hey Scotty I have a Toyota Avalon with 319k miles on it. The previous owners seemed to have taken good care of it and I drive a lot for a living. I want to change the trans oil and filter but now I'm not sure. Im curious to what you'd recommend thank you

  28. Wonder if a car with black fluid you could drain a quart every few weeks and replace with fresh fluid over a few months..might be ok if you did that. Not shock transmission with new fluid.

  29. I just bought a 08 mazda3 with 98,000 miles. Should I change the fluid and filter or leave it alone? Currently runs and shifts great. Just wondering

  30. I have a 2004 Chevy Tahoe with the 5.3. It’s started to slip a little bit and have a few hard shifts every once in a while. AT fluid was changed at purchase, approximately 90k, I’m at 146k now with these issues. Fluid still looks nice and clean, do I replace the fluid, or is something else going on?

  31. Great video Scotty. 😊👍Change the Oil on every axle and gearbox on my Toyota Hilux. The old oil looks great, but i do like you, better to be safe, than sorry. Thanks for great advice😎👍

  32. Telling people not to flush their transmissions is not good advise, a spill and fill is definitely not going to be as good as a full flush. A forward flush won't cause any harm, a reverse flush from a machine is how you get dirt in places it shouldn't be.

  33. He Scotty I appreciate your advice!!! I just bought my brothers 2007 Toyota Prius with 145k miles on it. These cars supposedly have the “lifetime” transmission fluid. It has never been changed. With this kind of car and situation, what would you recommend?

    Thanks!!!

  34. Scotty
    I have a 2011 Infinity G37 with a 7 speed auto trans. There isn't any dip stick or drain plug in the transmission. The owner's manual says its lifetime and there is no need to change the fluid.
    Should I schedule an appointment at the dealer or where else would you go to have the fluid changed?
    Thank you in advance!

  35. What about my 2012 Toyota Camry? Since i bought it..i never flush or change the transmission oil. Cause you didn't need it after 100,000 miles…
    Well.. now has 150,000. And i hear so many opinions about this..Should i bring it to a mechanic to do a flush?

  36. Hi @Scotty : recently about a week back, I have changed my cvt transmission fluid from local toyota dealer. They changed the transmission oil (4L new toyota CVT oil they put) and done the calibration after that. Now whenever I make the gear shift (N-D, N-R) the car has a jerk or vibration. The local dealer use toyota tech stream to scan and says CvT oil pressure and other values are ok, they unable to find any issue. Please note that Before chaging the oil I don't have the issue.

  37. Lol Scotty I got the point but you posted motor oil n oil filter instead of atf type filter n trans fluid. Just giving you a hard time tho! This helped a lot! Darn Ford n the 5r55s Trans without a dipstick! I hate checking it underneath n then having to have stupid lil tools/accessories to fill it. Plus the bs with Mercon V really makes it harder cuz it’s a LOT harder to just run n grab some. Keep up the amazing info shows good Sir!

  38. Well, Scotty, have to disagree. I had a 1974 Dodge Charger, 727 Trans. Put 450,000 miles on it and, fluid was never changed. Per Chrysler, trans fluid was good for the life of the car. Trans never ever slipped. Yes, it appeared dirty, but, again, never any issues. So, while I will agree that you really should change it, I followed the manufacturer's advise, and did not.

  39. I bought a 2008 honda civic with 160,000 miles. Should I replace the transmission fluid? I don't know if it has been replaced.

  40. Does my 2012 have a transmission fluid filter? I’ve had the fluid changed but they’ve never mentioned the filter

  41. I was scared to change the fluid too. But after exhausted research i found this. What he failed to mention was how it is actually "adaptive learning" on your cars computer that destroys clutch plates and everything else. It adjusts based alot on viscosity of the fluid. It will self destruct without an adaptive learning reset. The other option is a slow (quart at a time) introduction of new fluid over several hundred miles. Quart every 100. Start with a tranfser pump down the dipstick you can buy off ebay for 20 bucks. Pull a quart then refill. Doing it slowly will also gradually clean out valve body's in the tranny instead of nucing them with to much new fluid. Too much new fluid cleans too well plugs up vavles in tbe tranny. Eventually you will want to drop the pan change the filter and refill. Do this till it turns pink again. If your already having tranny problems just save up for a new transmission this wont help.

  42. Interesting you say to never flush. I get why you say that but I'm wondering if it really is prone to cause more issues than just dropping the pan and changing the filter. In my F150 with the 6r80 its capacity is 17 qts, but when you do the pan drop and filter change you only lose about 4 – 5qts of ATF. Is it's barely 25% new fluid.. is that really enough to "refresh" the system?

    Thanks Scotty!!

  43. Scotty very valuable info. Got 02 Camry with 140k ..only tranny flush done at 90k. Should i drain and fill now. Color is not too red now but not black at moment of my tranny.. appreciate your feedback. Trying to make car last 5 more years giving fact has lower than average Miles

  44. I have a cat just like "yours" haha. Thank you for the advice, I have a toyota camry 2001 with over 120k miles and I am doing all the maintenance to keep it running.

  45. scotty kilmer should i stick with nissan cvt fluid or just get Valvoline cvt fliud. Is Nissan just pushing their product or its a must

  46. Sucks that I dont know if the original owners ever bothered to change the trans fluid. It's been acting up. Mainly in cold weather. Any ideas. Seems like changing fluid/ filter would cause more harm

  47. But its not going be danaging anyways with bad dirt fluid as sane as replace it for new one after 150.000 miles anyway ?
    One or another its going keep damaging isnt it ??

  48. Just bought a diesel truck allison automatic tranny.
    And trany its noise when taking off on hwy bout 2nd gear noly then run good and ahift good.
    I did replace outside small filter. Run lot better but the few fuid came out its all dirt and grey collor like metal color.
    Is it might trany worn out pretty bad and isnt good idea replace fuid then ?????

  49. My transmission on ford explorer 2004 has its reverse SLIGHTLY non responsive (LAZY), I have been running the truck like that for a while until one day I made a grievous mistake of parking the truck on a steep spot with the truck nose was down..! that was the last straw that broke the camel's back for the reverse shift… I was busy firing the engine and with help of some people pushing the truck to get me out of the ''steeppy'' situation… but not until I heard a crumbling sound which I was sure came from the transmission… I drove home fingers crossed never to need to reverse the vehicle… I made it! … do have to change the entire transmission or there is another way out to fix the transmission…?

  50. So, as long as we don't flush or drain the torque converter, and just do a simple drain and refill of the tranny, we are okay?

  51. Hey Scotty love ya! I'm a 67 year old east tx. Granny. I have a 2002 ford sport track. It has 186,000 miles. My husband always changed oil about 3,300 miles but not trans. Fluid. Around 120,000 miles the truck started not to go into overdrive until 50 miles hr. He did drain the fluid,new filter and did not flush it from veh. That was about 65 thousand miles ago,still delayed in overdrive, not too great on gas mileage. But still running great! Bought it new 18 years ago,changed spark plugs,filters,just doesn't get great gas mileage. Any suggestions to help😁 granny in yam ville tx.

  52. The tranny on my dodge avenger was not touched until 154k miles. I had the filter and fluid changed with a pan drop, the fluid was dirty but not gunky. The transmission did not fail once new fluid was put in. New clean fluid is always better than dirty. The dodge mopar aft +4 is ultra premium synthetic fluid that lasts a very long time, it wasn't recommended to change the fluid and filter until 140k miles in the manual. The tranny shifts very well, it seemed happy after the fluid and filter change.

  53. I have a 300 000 kilometers transmission with medium rare dirty fluid and does not smell burnt. Lil bits of tranny problem will lucas stuff help ?

  54. The transmission is getting worse because you didn't properly did a transmission fluid change. You must reset the transmission computer (TCU) becuase it will adapt different pressure with the new fluid. Running it without the reset will still have the memory of the old fluid which most likely cause issues.

  55. My 2012 honda civic hasnt had an auto tranny fluid change since I got it, if the fluid looks ok, should I process with the flush and fill? 85K MILES without change, manual recommends 60k

  56. I have a 2001 crv, I got it at 40,000 miles from my grandparents. I have only done drain and refill once about 30000 miles ago. Should I continue to do the empty and replacement, I currently have 107,000 miles. Any advice is appreciated.

  57. I have a 2001 Mitsubishi montero sport xls and having grinding noise in my transmission if I change if filter and fluid do you think the transmission will go out?

  58. I had an 2005 Malibu maxx that hit 350,000 miles with original engine and transmission. I never touched the trans oil lol!! I wonder how dirty it was? Still ran like a champ when my brother traded her in for a Prius still miss that car everyday!

  59. By maintenance it sounds like some of you mean 'change the oil'. Wrong. Maintenance is checking the transmission for issues – the oil is the life blood of the transmission. If you change it, you change the dynamic of the system that will tell you when something is going wrong. The best thing is to nip the 'wrong thing' in the bud. Check the transmission, adjust the adjustable things, notice how it shifts, etc. Then if the oil is beginning to discolor or get dirty, change it and do a thorough examination – the oil should not get dirty, something is going wrong if it does.
    There is no mileage aligned with this. Scotty says 40 – 50K miles because people need some kind of guideline rather than do maintenance and learn how to check their oil for deterioration. OK it's a good trade off.

    You change oil on your car so that you can waste oil. It depends on how the car is driven and its environment when it is running. A highway car can go for 10 – 100 times as far on an oil change as a short drive car. Check the oil in the engine – if it is NOT getting dirty, change to another brand. When the oil begins to break down, time to change the oil. It does not matter if it is 1000 or 10,000 miles. My driving allows me to get between 8000 and 12000 miles on an oil change. So I do. I use Amsoil and have found it to be the best price per mile. Their 5W-20 is like $6.50 per qt and compares to any other synthetic on the market very favorably. I am not a salesperson for Amsoil, but I do use it in all of my vehicles. I use the 15,000 mile change oil, but it never makes it to that point. I check it and determine whether it is in need of an oil change. You can tell when the oil is beginning to breakdown. If you wait too long, the engine begins to suffer damage. Many people avoid the problem of determining when the oil needs changing by using a brainless schedule to change oil and waste a lot of perfectly good oil life. But better waste a little oil than damage the engine.

  60. I have a 2016 Mitsubishi Outlander I got 3 years ago with only 25 miles on it. Now I’m at 52,000 miles, should I change my fluid?

  61. On my Merc, the trans fluid has never been changed by the previous owner and it now has 175k miles…i guess i shouldn't changed the fluid

  62. I do a drain fill every 20,000 and when I pull the plug it is always very clean. At 160,000 I have never dropped the pan or changed the filter on the Nissan Frontier.

  63. When I was a young mechanic we ate the whales and used the leftover grease for transmission oil in our buggies …the bones went to the dogs…..we had BIG dogs

  64. I have a 2003 Corolla. Flushed the transmission once. No problem. Besides regular maintenance I've only had to change the starter. 276000 miles and still going 👍

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