I spoke with a service shop about getting my transmission fluid changed (in my 2014 Kia Rio 6 speed auto). I was curious if they could get more of the fluid out than myself just dropping the drain plug on the transmission at home (which only get about 35% out).

He said that my transmission do not have cooler lines, and they they go in from the top filler hole with a tube and then run it through the gears and remove fluid using this tube.

In this methodology, is it possible to get the majority (like 90%) of the fluid out? I don't want to pay all that labour if I can get similar results from the drain plug at home.


  • What makes you think you'd only get 35% out through the drain plug (although you'd usually drop the pan, replace the filter, etc)? If it doesn't have a cooler loop I'd expect you'd get more.
    – GdD
    Commented May 18, 2023 at 16:52
  • I've never heard of an automatic transmission without a cooler loop of some kind, so that is bothering me. Heat is the killer of automatic transmissions. The better you keep the heat down, the longer it will last. Next, while you can pull a lot of fluid from the transmission, pulling in excess of 90% is going to be very difficult due to one big issue: the torque converter. Even with the engine off, ~1/2 of it is going to be full of transmission fluid. No way you're going to pull that out of there running an extraction hose down the dipstick tube. Commented May 18, 2023 at 17:13

2 Answers 2


With over 20 years as an auto service technician I can tell you that any % exchange quote is purely a sales figure. There are methods of replacing all the fluid in an automatic transmission 100% which includes the valve body, torque converter,cooler lines, heat exchanger etc but it requires specific machines that connect in line with the closed loop of the transmission fluid system. I know of only 2 ways this is accomplished. (1) connect via cooler lines or (2) connect to fluid pickup by removing the screen or filter. Both methods introduce new fluid via a pump and use it to push out the old. Any other method causes mixing of old and new with repeated evacuation or draining and refilling with new until a "new looking" fluid condition is achieved. No one method is universal as not all automatic transmission have cooler lines and/or wet sump filter/screens. For example many Honda transaxles cannot be serviced by any of the methods mentioned above. Also CVT and Dual dry clutch type automatic transmissions also cannot be serviced this way either. In all cases follow the manufacturers recommended service intervals and most importantly the correct fluid for your application as there is no universal fluid in existence.

  • When you say there is no such thing as a universal fluid, are you recommending not to use a universal fluid that specifically states that it meets my cars transmission fluid spec? I was consider Valvoline Maxlife that meets Kia SP4 spec....and many people who use it say it is great.
    – Scorb
    Commented May 18, 2023 at 22:37
  • "Universal" means it fit all applications or specifications. There is no such fluid. Val MaxLife does meet the requirements for many applications but in no way is it "universal". It is a great option for many but not all. i.e. Ford Merc VI, Chrysler AP+4 to name a couple.
    – ShadowHemi
    Commented May 20, 2023 at 14:06

No. Draining the oil and running the transmission through the gears to get more oil out is likely to damage your transmission. You should never run a transmission without oil. You will burn up clutches and end up with internal leaks.

When dropping the pan, you will only drain 2.5 liters. Whereas, the full transmission capacity is 6.1 liters. Therefore, you will not get 99% out as you already know.

The only way to get the remaining fluid out is to open the transmission relays with a scan tool and push the fluid out with a fluid exchanger.

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