My 2003 Toyota Camry has over 100k miles. I believe the previous owner never changed the transmission fluid because it look black and smell burnt. I took it to an auto shop for them to drop the pan, change the transmission fluid and filter. How do I know if changing my transmission fluid and filter resurrected or killing my transmission?
How do I know if changing my transmission fluid and filter resurrected or killing my transmission?
Was the trans slipping? Shifting funny? If not you are probably helping it. If it needed “resurrecting” which to me means it was already having problems, you may just be delaying the inevitable. It’s really hard to say without driving or even seeing the vehicle.
New fluid and a filter can’t hurt. There are lots of old wives tales about changing the fluid and the transmission goes out a week later. I personally don’t believe that but opinions differ.
If the fluid smells burnt, it needs changing. It won’t all drain out with the change but I suggest having another change and filter at about 30,000 miles or sooner if the fluid smells burnt.
Your Camry probably needs the Toyota T-IV ATF and I doubt the transmission shop used the correct fluid. The alternate would be synthetic fluid which is usually more expensive than the Toyota brand. Check your receipt and if the fluid used is not the correct one, then you need to drain and refill it. This is easy on your car, there is a 10mm hex drain plug, it has a crush washer (buy new ones from the dealer). You need to drain and refill at least 3 times to get most of the fluid out.
If the transmission fails in a month, year, or even several years it won’t be because of the fluid change. It will be due to the fluid never having been changed and/or a possible transmission issue which was neglected.
Black and smelly fluid means the fluid has been overheated and contaminated due to friction material being scrubbed off the clutch packs. That usually means damage exists to some degree.
Change the fluid and hope.
Unless you have symptoms or a reason to believe the shop that did the service made a mistake, just drive on, normally. Automatic transmission don’t last forever, but yours probably has a lot of miles in it still. It does sound you made the right call to get it serviced. Some (or maybe all) Toyota’s say the transmission doesn’t need routine service, so there is no service interval recommended. But it is usually better to routine service most newer automatics on at least a 60k interval. 100K is in the ballpark. What does the owner’s manual say about routine service interval?
Now that the the pan has been dropped and the filter changed, have a complete transmission fluid exchanged performed.
When transmission fluid is burnt and smells, it means the transmission has been running hot. This is due to the friction modifiers in the transmission fluid breaking down and causing slipping between the clutch packs.
If you just drop the pan, this only removes about 30% of the total amount of transmission fluid that the transmission holds. The rest is held in the torque converter, the valve body, the transmission cooling lines, and in the transmission cooler in the radiator.
So only adding 1/3 of good fluid to a system that still has 2/3 of burnt/used up fluid only contaminates/breaks down the good fluid with the old fluid.
If you have the transmission fluid exchange performed, only then you can say that you did everything you could to save the transmission.
Tester
Totally agree with @Tester Do this and hope for the best. Then keep an eye on the condition of the fluid.
Our Toyota was having slight trans shifting issues. We changed fluid and the shifting “feel” improved. New fluid will not fix any broken mechanical part in trans but it may help with issues like delayed shifts or other minor issues.it may affect cold shift issues or hot shift issues. Some cars are touchy. Some owners see dirty fluid and experience no issues. They change fluid and trans shifts the same, that is, no better, no worse.
@GeorgeSanJose The manual say to change the transmission fluid every 60k miles.
@Tester By fluid exchange, do you mean flush the fluid, cause it is the only way to get completely all of the fluid out ? Most people say that flushing the fluid only harm the transmission.
A fluid exchange/flush are the same thing. And those who say this service will harm the transmission are still living in the 80’s, have never used or even seen one of these machines, and are basing their opinion on urban myth.
Here’s how these machines work
The inlet transmission cooling line is disconnected from the radiator. The machine is connected to the cooling line and the radiator so the machine becomes part of the closed loop system. The machine is then filled with new fluid. The engine of the vehicle is then started and the pump within the transmission begins to pump out old fluid into exchange machine while at the same time the machine returns new fluid back into transmission. This process continues until the fluid coming out of the transmission is the same color as the new fluid going into the transmission. This replaces all the old transmission fluid.
Now, if damage has already occurred to the transmission from the lack of maintenance, nothing is going to save the transmission. But if the transmission is still functioning properly, I’d do the fluid exchange to keep it that way.
Tester
@Tester
you forgot to mention one very important thing . . .
Most shops that use the trans flush machines do not remove the pan
They do not replace the filter and gasket
In my opinion, a flush is stupid, if you’re not going to replace the filter and gasket, also
@db4690 … Tester in his post above didn’t claim a flush was the same as dropping the pan and changing the filter, just that – contrary to some claims – it doesn’t harm the transmission. I think common sense says there is merit to having a transmission flush. Certainly better than doing nothing at all, if it is done correctly, a flush almost certainly helps by introducing some fresh fluid into the system. Who knows for certain whether a flush exchanges 100% of the fluid, but neither does dropping the pan and changing the filter and re-filling. Maybe the best combo of all is to drop the pan, clean out the bottom of the pan, check for filing, change the filter, then replace everything, and do a flush.
@Tester … just curious, in your experience how many quarts of new, fresh transmission fluid is required for a typical transmission flush? I understand it probably varies car to car, but say compared to the total transmission capacity of the transmission. So if the transmission has a total capacity of 10 quarts for example, how many quarts of new transmission fluid would be used in order to obtain the same color going in as coming out? You’d have to know how many quarts of fresh fluid you used, so you could charge the customer the correct amount, right?
I add 20% more transmission fluid to the exchange machine than the total capacity to refill the transmission.
Tester
@GeorgeSanJose
In a hypothetical world . . .
If my only choices are flush with no filter or pan drop with filter, I’ll pick the pan drop with filter
yes, I put more value on replacing that filter and having more of the old fluid remaining, versus not changing the filter, but pushing out more of the old fluid
That would be preference, in this hypothetical world
You know all that crud on the bottom of the pan, the stuff you have to clean out in the solvent tank?
Well, it’s there, even if you replace the fluid and filter often
I’m wondering if the flush will leave the pan as clean, if the pan is not removed
If it’s one vs the other, my vote is also for a pan drop and filter.
Another thing to consider is that if there is a lot of crud in the pan that crud will be sucked up when the pump is in operation and all of the crud too large to go through the filter will end up blocking pores in the filter and restricting the volume of fluid entering the transmission.
When the engine is shut off the crud then settles back into the pan.
Anything affecting fluid pressure and volume is not good on an automatic.
I’ve never had a transmission flush done any any of my vehicles, and never paid for a pan drop/filter, always have done it myself in the driveway, so don’t know how much either costs. Just curious, anybody know the appx cost of a transmission flush vs a pan drop/filter/refill? Cost to customer if done in an inde shop I mean.
I used to take my own ATF and pay the shop $99 to do it. This was around 2008. I do my own now.
No, for a pan drop, filter change. It was for a Dodge Caravan if it matters (probably filter and gasket cheaper than most other cars), I provided my own ATF4 (b/c of my OCD) and watched it being poured 
The second time I watched the newbie in the shop put the bolt on with the air gun without hand-tightening it 1st. I had to stop him and call the shop foreman. That bolt required special attention for the rest of the car’s life. Even though this was a good shop, still a new kid on the block was able to screw things up.