I have a 2008 Mitsubishi Outlander XLS V6 with a 111000 miles. Never changed the transmission fluid yet. Should I change it now?
Some shops say to not change it but I would like to get more use and miles out the vehicle. Which method is best to use a Transmission Fluid Drain and Fill? Or a Transmission Fluid Flush? Can I use AMSOIL Transmission Fluid instead of Mitsubishi Fluid?

 

Honestly, I would get a used oil sample to see what is going on.....

 

I have seen both sides of this question, one time I changed the old trans fluid on a car with no problems, but the second time I tried is on an a car with 120k miles, it bit me in the butt.

Here is the problem, Automatic Transmission Fluid contains a high amount of detergent in it. It's a cleaner with oil. If the fluid has gotten very old and stopped cleaning, there will be some build up in the system. What's the problem with that? Well if the new detergent removes the flakes of build up, they can get stuck in the tiny tiny fluid passages, causing a blockage.

Then weird things happen like not having a single gear and you have to force it from 2nd to 4th, etc. You get the idea. It's a gamble for sure.

My advice is to drain one or two quarts of the 7 at a time and don't do a complete flush fill. Every few months, if you introduce better quality fluid, there will be an improvement in fluid quality without hopefully creating any blockage.

To reinforce the other comment, perhaps an oil test would be the best way to go, you may have sufficient viscosity to continue with the same fluid.

Good luck

 

You should have changed it at least twice by now...but oh well. If it were my vehicle I would take it to a transmission speciality shop and have them do a complete flush and inspection. You need to get all the old fluid out and clean the entire system. It also depends on if you want to keep the vehicle for much longer...if not then just drive it till it stops I suppose. Best of Luck.

 

backing up binzd's response, putting new fluid in may disrupt old deposits and create more problems. Lancer is correct, tranny fluid *should* have been changed twice by now, but it hasn't so now OP gets to play with the consequences. If old fluid is left in, deposits will slowly eat the transmisison...deposits will act as sand in the fluid. If you "flush" the system, new fluid detergents may break up deposits too fast and cause issues. If the fluid were to be changed, a drain/fill might be best as that only changes out 2.3Qts per drain. If I were to do that, I might do that ever other oil change...which is 15k miles for me.

 

If you want to keep the vehicle..and it is in otherwise good shape...Take it to a shop that knows transmissions well...have the tech do a really thorough inspection and see if its even worth going further. If they do it right..they will extract 100 % of the old fluid and replace it with new Mitsubishi spec fluid...anything less will have little or poor results and as others have said...it potentially could make things worse.


There are places that are fully aware of the horror stories of partial flushes and drain and fills. A competent transmission tech will bring the vehicle back to almost new condition as long as severe damage has not already been done.Best of Luck..let us know how it works out for you.

 

I would suggest changing it. Do the flush method described in the sticky near the top of the page. It's not hard. Yes, amsoil.

 

Should I take it to a Mitsubishi dealership? Do they offer any warranty on their work? Also thinking about Firestone they both do a flush. Which would be the best option?

 

Dealership will warranty their work, but really that is only saying they will ensure proper fluid, amount of fluid, and where they put it. That will not warranty your transmission won't fail because of the situation you are in.

I think you need to confer with a transmission shop and then have them do it. I say have them do it because you are asking for their expertise in transmissions and fluids. Mitsu will not care and likely won't know as well as tranny shop.

 

Can I use AMSOIL Signature Series Multi-Vehicle Synthetic Automatic Transmission Fluid instead of the Mitsubishi fluid?