05-09 mustang automatic transmission reliability? (5r55s)

Hey everyone,

I am in the market for a new project car and daily driver. I found a 2005 mustang GT with 104k miles for a good price. Super clean. Asking $6200 firm. Generally speaking the 4.6 3v engine is bulletproof and as long as you don’t overheat it and keep fresh oil in it, they can easily last to 300k+ miles. The only thing I’m concerned about is the automatic transmission. Specifically it is a 5r55s. These auto transmissions were in the 05-09 mustang v6s and GT’s as well as early 2000s Ford Explorers and Mercury Mountaineers as well. Some of these cars I’ve seen ads for with these transmissions have very high mileage like 200-250k but I’ve also read about quite a few people online having theirs go out at 100-150k or sometimes even less.

The owner I’m buying the 2005 GT is the original owner and the only thing he’s replaced other than essential maintenance (like tires, brakes, oil changes) is the coil packs due to a misfire. Everything else is original. He says he’s never had any issues with the transmission. I know transmission life comes down to maintenance, how the cars been driven and luck of the draw but…My question is; if I change the transmission fluid and filter as soon as I buy the car do you think I’ll be ok? Or is one of these 5r55s tranny’s a ticking time bomb with 104k on it when it’s never been serviced? The car is 100% stock with no aftermarket mods which is somewhat encouraging because it likely hasn’t been raced or beat on too much. What do you guys think about this? And the car in general for the price I’m getting it at? Anyone have experience with owning or working on vehicles that use this 5r55s auto trans? If so how many miles has it lasted you/the owner? The bad things I’ve read about this auto trans is the only thing that’s preventing me from pulling the trigger on this car. And before anyone asks…I commute to work and drive in traffic a lot so manual is not an option for me.

No experience myself. But overall it looks ok. Known problems, here’s what I’m seeing … You can probably get more info if you google those TSB numbers

07N08: Solenoid replacement warranty extension
9-12-12: servo pin case bore wear causes 2-3-5 shifting problems
GSB-66: A/T Cooler flush procedure

So you aren’t keeping the 2011 V6 with a better transmission but buying an older V8 with concerns about the trans? OhhhKaaayyy

A one owner, unmodified, 05 is likely a good bet. Change the fluid and filter when you buy it and again at about 135k just to get the rest of the old ATF out. Should be fine for 100k miles.

Maybe unpopular opinion but I like the older s197 body style better. Also l’ve owned 2 v6 mustangs now and wanted to get a v8 (coyote is slightly out of my budget…) I guess I downgraded a bit interior wise but since they’re about the same mileage I’d say I came out on top since I sold the 11 v6 for 10k and I’ll have some leftover money to work on this build

I’m of the strong opinion that auto complaints should be taken with a grain of salt; or lots of grains. The simple reason is that the vast majority of complainees will never believe for one second that their lack of maintenance habits had anything to do with the failure.

On an anecdotal basis, my daughter has a 2005 Mustang with that transmission and it still shifts and operates like new at about 230k miles. Of course she has deviated from the norm and actually has it serviced on a regular basis.

My son owned a Lincoln Aviator with that trans and it was also reliable. Reliable right up to the point when the lead footed person he sold it to decided to roll it…

How many miles did the aviator have?

That does not matter. You are buying a used vehicle so just because one went x number of miles on the transmission does not mean yours will . You might get great service or it could fail on the way home.

The mileage on the Aviator is irrelevant but at the time it went over on the roof and became a total I think it was near a 100k.
And the woman who bought it drove the beejeezus out of it; which is why it got wrecked. Lead foot and 3 to 4k miles a month.