BTFanC300

Hi, I recently bought a used 2014 C300 (engine 156 and transmission 722.9) with 120k miles (mostly highway) here in Montreal, Canada. Engine oil changes done regularly, but I don't think the transmission fluid was ever changed.

I noticed that when down shifting, sometimes the gear change will kind of jerk/jolt the car a little bit. It doesn't always happen, but happens sometimes. I just tried resetting the adaptive throttle system so I'll see how that goes.

Regardless, my user manual says to change the transmission fluid every 6 years or 75k miles. Should I do it now? Is it true that doing it this late can break my transmission?

Thanks!

BTFanC300

Anything?

Alfadude

If you have concerns it was never changed, change it. Not sure where you heard you will "break it" if changed later than recommended. Look at it this way, if it wasn't changed and it is now 50K miles overdue, if you just leave it are you saying that after a certain number of miles it is going tomagically get better and all is going to be well? Logic would tell you there is no upside to leaving it as is. Change it and don't look back.

BTFanC300

There are lots of articles online about changing old fluid damaging the transmission (due to moving dirt around, etc.). My mechanic told me it's not something that generally needs to be changed, and mentioned that he only changed it in his car at 155k miles.

That's pretty much why I'm asking.

Alfadude

There's a reason it is part of the maintenance schedule from Mercedes. If you do a search on here (or a lot of other forums) you will see a lot of members that change their fluid regularly without incident. I can't say I have ever seen a post where someone grenaded their transmission because they changed the fluid properly. Do what you feel comfortable with.

BTFanC300

I don't think you're understanding. I never said changing regularly can damage it. The debate is whether it's a good idea to change it on high mileage cars that have never had it changed before. In my case, the manual says 75k but I'm at 120k. If I was at ~75k this wouldn't even be a question lol..

Alfadude

I understand what you are saying. You have two options to consider. One is to at this point totally ignore the maintenance schedule and never change the the transmission fluid as long as you own the car and just see what happens. The other is to finally change it and then keep wth changing it every 75K after. Which one provides less risk? I would think changing it is the best option. Sounds like you are leaning towards not changing it. Up to you. But I will say it wouldn't surprise me if you have it changed and then come on here and say what a nice difference it made.

xsever

I read too about some people claiming that changing it after a long time broke their transmission, but I think a badly maintained transmission is bound to fail anyway.

If you end up changing it, making sure both the pan and the torque converters are drained to remove the entire old fluid. Draining the pan only will not cover all the fluid housed inside.

Make sure you use the MB 236.15 approved fluids which can be found here: https://bevo.mercedes-benz.com/bevol...236.15_en.html

I would definitely change it before that transmission destroys itself sooner than later.

C300CA

"moving dirt around" happens during both normal driving and fluid change.
I have other cars that already passed a lot the Transmission fluid change due mileage, and at one point I had it changed, no hurt. My C skipped one time then changed at next due, no hurt.

BTFanC300

I'm planning on keeping the car for another 3 years, but I really don't put much mileage. Less than 4k a year. Is it worth changing?

xsever

Definitely! Imagine not changing your engine's oil for this long. Think of all the moving metal parts inside the transmission that are now housed inside this old old and dirty fluid.

The fact that the transmission did not fail yet is a testament to MB's high-quality parts inside it, but that does not mean that the fluid change is not necessary. It says 75k miles or 6 years for a reason.

It's up to you at the end, but if that transmission fails or the fluid pump fails within the 3 years, it's going to be very expensive to repair.

Adi-Benz

I have to agree on the statement that many people have in fact damaged or created more problems by changing the transmission oil on the 722.9. there's a good chunk of issues caused by changing the oil for some reason.

You SHOULD do it, but DO NOT do a flush. And take care when doing it. Even the dealers mess it up somehow.

Colin G

Change it.

When I buy a used car, all fluids get changed no matter what.

I don't trust any ham-fisted maniac that may have previously worked on it. Dealerships included.

dennish

I was advised by a MB Indy who strongly told me to not flush these transmissions. Drain including the torque converter, change filter, and use MB approved fluid.

shotgun_banjo

Change the fluid no other choice unless you want to risk it. A $450 job is cheaper than a $8000 tranny.

Donald McPherso

I would change. Those who had problems after change probably had problems before change and hoped change would fix.

alx

nevermind. wrong thread

Alfadude

I wonder what the OP ended up doing.

CJG

They can’t post because they’re sitting on the side of the road.
Perhaps not changing the oil for 50,000 miles is also a good choice. 🙄

xsever

Hahahaha

ice947

nevermind...if you have to ask to do tranny fluid...im in awe...

BTFanC300

nothing to be in awe about other than you being unable to read. there are countless articles about the potential dangers of changing the transmission fluid on a high mileage car that never had it done before. maybe do some research next time you're in awe

BTFanC300

Right, because engine oil and transmission fluid have the same maintenance schedule.... not like one is changed 4x time frequently than the other... no not at all.. let's ignore that

BTFanC300

I haven't done it yet but I've been looking into it. Only put on about 4000km since I created this thread, I drive very short distances.

Dealer wants to charge 450$ plus tax so I'm trying to find an indy but some don't want to do it. Apparently it isn't as simple as it sounds.