Originally Posted By: RPMster
Please share your personal experience with automatic transmission longevity in your current and past vehicles.
How were they used: Easy freeway commutes? City driving? Heavy loads?
How did you maintain your automatic transmission: OCI, drain/fill or flush, serviceable filter, factory fluid or multi-vehicle fluid, DIY or dealer/shop, etc?
Did the transmission have any factory defects (either non-typical defects, or well known defects that were common to that vehicle model)?
Any other details that might be relevant?
I have personally maintained my vehicles and the vehicles owned by my immediate family members (parents / brother / sister-in-law / brother-in-law / etc). I have never had a transmission failure or any kind of other transmission problem with vehicles that I have maintained.
My first car was a 1996 Chrysler Intrepid (Dodge Intrepid for our American friends here!) My dad bought it brand new, and then got a company car a year later, so I assumed use and care of this car (and eventually bought it off him as he simply didn't need it). Car was used for in town commuting, lots of downtown city driving, frequent trailer towing to cottage country at 70+ mph (jet ski trailer - about 1,000 lbs), and other miscellaneous use. I don't abuse any of my cars, but I generally do not drive "easy" either. This car (as many Chrysler products of that vintage) had a terrible transmission, and they were prone to failures either within or right after the warranty period. I first changed the fluid at 80,000 km with Amsoil ATF, and added a nice sized transmission cooler inline with the built-in stock radiator cooler. This took me to 160,000 km, when I changed the fluid / filter once again with Amsoil ATF, and never touched it again until I sold the car with 330,000 km on it. No transmission problems whatsoever, and car shifted perfectly when I sold it.
My mother had a 1997 Oldsmobile back then. I changed the fluid at around 100,000 km to Mobil 1 synthetic ATF. Never touched it again, and the car worked perfectly until it was written off in an accident (not her fault) at around 220,000 km. No towing, relatively easy driving (but mostly city with some infrequent highway trips).
My family inherited a 2001 Chevrolet Venture from my dad's company back in 2003 (for next to nothing compared to what it was worth). This van is now mine (as an extra vehicle / work-horse / trailer towing vehicle). It is no longer driven on a daily basis. Transmission history... First changed fluid to Amsoil ATF around 90,000 km, and added a large transmission cooler at the same time. Vehicle started towing duty shortly before this happened. I've changed the ATF / filter once again at 180,000 km with Amsoil, and the last time was around 240,000 km. The van now has over 300,000 km, runs and shifts perfectly, has had no internal engine or transmission work, and does very frequently pull heavy loads (right up to it's maximum trailer weight rating and/or cargo rating). In the summer, it pulls a trailer almost every weekend, but it is seldom used in the winter. I also load it up inside with heavy household items (drywall, paving stones, gravel bags, etc) in excess of 1,500 lbs. No issues. Largest trailer load that was towed on multiple occasions was up around 4,000 lbs. Still no issues. This van was directly involved in building / completely renovating 2 houses over 4 years. I'm sure the van will rot from rust prior to me having any tranny issues!
My parent's current cars are too new to really glean anything from longevity, but I have changed each of their transmission fluids with factory (Mercedes-Benz approved) synthetic fluids both at 60,000 km. They are now coming up onto 120,000 km, where I will again change the fluid and filters for them.
My wife's car is a 2006 Mazda 6. These FNR transmissions are not known for longevity if they are not maintained, and with a suitable fluid. We bought the car used back in 2012 with 90,000 km on it. No tranny service before that. Fluid was pitch black and shifts were not smooth. I changed several times since then with Amsoil ATF, and did a pan drop / filter change once. Shifts are much better now. I will be adding a cooler to this vehicle as we will start towing a small trailer with it next year. It is currently at 140,000 km with no issues other than a slightly firm 1-2 shift when the tranny is cold (first couple of shifts in the morning). This seems to be common to the 2006 model year, and is likely due to bad programming. No other issues (yet)!
Both my current vehicle and previous vehicle (daily drivers) have had manual transmissions, so I can't offer any other experiences past the ones above regarding automatics, but so far, I think I've had all good experiences with the auto's in my family. I think maintenance is key, and keeping the fluid temperatures in check if the vehicle will be used for any kind of towing / hauling, or if factory cooling is marginal in the first place. Transmission fluid does not have to be as hot as engine oil, nor should it be.