SL/R231: Rough shift when cold
Thread Starter
MBWorld Fanatic!
Joined: Dec 2015
Posts: 1,633
Likes: 520
From: Hagerstown MD
2015 SL400; 2019 X5M40i
Rough shift when cold
Drove the SL on a 400 mile road trip. On both mornings, temps in the 40s the transmission seems to take a seconds or so to engage P or D. The first several 1-2 shifts seem rough but once the car is driven for a short while all is fine. I had the transmission serviced last year at 30k miles by my dealer. No warning lights or other issues. Should I be concerned?
Banned
Joined: Nov 2025
Posts: 477
Likes: 187
From: US
Mercedes SL R231
Hmmm, sounds like it is slow to build pressure. I haven't been out recently when the temps are in that range, but I'll pay close attention the next time I do.
Years ago, and I mean YEARS, I had a 1978 Cutlass Supreme and one zero degree morning in NY states, the car was very slow to shift when first started. Never happened again, so I don't know what to say.
Do you start off in E or S mode? It shouldn't matter since even in E mode the tranny will start in 1st gear until warmed up.
Years ago, and I mean YEARS, I had a 1978 Cutlass Supreme and one zero degree morning in NY states, the car was very slow to shift when first started. Never happened again, so I don't know what to say.
Do you start off in E or S mode? It shouldn't matter since even in E mode the tranny will start in 1st gear until warmed up.
Thread Starter
MBWorld Fanatic!
Joined: Dec 2015
Posts: 1,633
Likes: 520
From: Hagerstown MD
2015 SL400; 2019 X5M40i
Hmmm, sounds like it is slow to build pressure. I haven't been out recently when the temps are in that range, but I'll pay close attention the next time I do.
Years ago, and I mean YEARS, I had a 1978 Cutlass Supreme and one zero degree morning in NY states, the car was very slow to shift when first started. Never happened again, so I don't know what to say.
Do you start off in E or S mode? It shouldn't matter since even in E mode the tranny will start in 1st gear until warmed up.
Years ago, and I mean YEARS, I had a 1978 Cutlass Supreme and one zero degree morning in NY states, the car was very slow to shift when first started. Never happened again, so I don't know what to say.
Do you start off in E or S mode? It shouldn't matter since even in E mode the tranny will start in 1st gear until warmed up.
Banned
Joined: Nov 2025
Posts: 477
Likes: 187
From: US
Mercedes SL R231
I start in S mode because I fear low speed pre ignition (LSPI). I'm pretty sure the "low speed" refers to engine speed and not vehicle speed. The extra load starting in 2nd may (or may not) increase the likelihood of LSPI. I really don't have any idea if that is true or not, but starting in 1st is less of a load than starting in 2nd.
Thread Starter
MBWorld Fanatic!
Joined: Dec 2015
Posts: 1,633
Likes: 520
From: Hagerstown MD
2015 SL400; 2019 X5M40i
I start in S mode because I fear low speed pre ignition (LSPI). I'm pretty sure the "low speed" refers to engine speed and not vehicle speed. The extra load starting in 2nd may (or may not) increase the likelihood of LSPI. I really don't have any idea if that is true or not, but starting in 1st is less of a load than starting in 2nd.
MBWorld Fanatic!
Joined: Feb 2021
Posts: 1,419
Likes: 737
From: Nor-Cal
2020 GLC300 -2014 Sl550 - 1997 SL600
I don’t remember, but what’s your mileage? 30k? Doubt it’s transmission itself.
Sometimes if the transmission is slightly under filled it can exhibit behavior like this in cold weather.
These transmission fluid levels are set using temperatures. It’s easy to get them “close”, but just slightly off.
Sometimes adding just a bit of fluid can solve this. It’s not something I would do Willie Nilly, but you may want to mention that you’re having cold weather shift issues to the place that did your transmission service. Give them a call.
Good Luck
Last edited by crconsulting; Nov 6, 2025 at 12:59 PM.
Trending Topics
Thread Starter
MBWorld Fanatic!
Joined: Dec 2015
Posts: 1,633
Likes: 520
From: Hagerstown MD
2015 SL400; 2019 X5M40i
Have you driven it in the cold anytime before this and the time you had the transmission serviced?
I don’t remember, but what’s your mileage? 30k? Doubt it’s transmission itself.
Sometimes if the transmission is slightly under filled it can exhibit behavior like this in cold weather.
These transmission fluid levels are set using temperatures. It’s easy to get them “close”, but just slightly off.
Sometimes adding just a bit of fluid can solve this. It’s not something I would do Willie Nilly, but you may want to mention that you’re having cold weather shift issues to the place that did your transmission service. Give them a call.
Good Luck
I don’t remember, but what’s your mileage? 30k? Doubt it’s transmission itself.
Sometimes if the transmission is slightly under filled it can exhibit behavior like this in cold weather.
These transmission fluid levels are set using temperatures. It’s easy to get them “close”, but just slightly off.
Sometimes adding just a bit of fluid can solve this. It’s not something I would do Willie Nilly, but you may want to mention that you’re having cold weather shift issues to the place that did your transmission service. Give them a call.
Good Luck
Thanks. Dealer is 60 miles away but I'll see what they say.
MB World Stories
The Best of Mercedes & AMG
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
Mercedes Teases Updated EQS With Steer-By-Wire and a Yoke
Verdad Gallardo
8 Mercedes Models With Poor Reliability Records
Verdad Gallardo
Thread Starter
MBWorld Fanatic!
Joined: Dec 2015
Posts: 1,633
Likes: 520
From: Hagerstown MD
2015 SL400; 2019 X5M40i
@rmorin49 Cold this morning. Still having the problem?
Is it definitely true that the tranny starts in first gear when cold even in E mode when the dash indicator says 2?
Last edited by rmorin49; Nov 10, 2025 at 09:00 AM.
Banned
Joined: Nov 2025
Posts: 477
Likes: 187
From: US
Mercedes SL R231
I will try to find where I read that the tranny goes to first gear when cold. Could not find it searching the owner’s manual. Maybe in a 7G tranny tech bulletin or something. I’ll post when I find it.
Banned
Joined: Nov 2025
Posts: 477
Likes: 187
From: US
Mercedes SL R231
I found this comment, but am still looking for an official statement.
https://mbworld.org/forums/glc-class...m_content=post
https://mbworld.org/forums/glc-class...m_content=post
Thread Starter
MBWorld Fanatic!
Joined: Dec 2015
Posts: 1,633
Likes: 520
From: Hagerstown MD
2015 SL400; 2019 X5M40i
I'm going to do some experimenting tomorrow morning. Supposed to be 29 degrees. I would expect it will take up to 10 minutes of driving to get to "normal" operating temperatures. Lots of stop signs in my neighborhood to see what gear is used at each start.
Thread Starter
MBWorld Fanatic!
Joined: Dec 2015
Posts: 1,633
Likes: 520
From: Hagerstown MD
2015 SL400; 2019 X5M40i
Conducted my experiment this morning:
1. Ambient temps were 30 degrees F. Car was parked in a non-heated garage.
2. Started the car and let it run for about 30 seconds.
3. Backed out of the garage into the alley behind our home about 100 feet.
4. Car in E mode. Dash showed second gear.
5. Very slow acceleration, after only about 2 seconds felt what I feel was a shift from 1st to 2nd gear. Dash still said second gear.
6. After approaching the street I stopped and started out again. Same thing, what felt like a shift from 1st to 2nd gear.
7. I drove around for about 15 minutes, making several stops with the same result.
8. Went onto a highway and drove at 45 - 55 mph for another 10 minutes.
9. Made several stops in E mode and did NOT feel any shift until it went from 2nd to 3rd gear.
10. Changed to Sport mode to start in 1st gear. Tranny holds in first much longer than it did when starting in E mode with a cold engine.
I am convinced that the transmission does indeed start in 1st gear when cold and in E mode.
Would welcome others to chime in.
1. Ambient temps were 30 degrees F. Car was parked in a non-heated garage.
2. Started the car and let it run for about 30 seconds.
3. Backed out of the garage into the alley behind our home about 100 feet.
4. Car in E mode. Dash showed second gear.
5. Very slow acceleration, after only about 2 seconds felt what I feel was a shift from 1st to 2nd gear. Dash still said second gear.
6. After approaching the street I stopped and started out again. Same thing, what felt like a shift from 1st to 2nd gear.
7. I drove around for about 15 minutes, making several stops with the same result.
8. Went onto a highway and drove at 45 - 55 mph for another 10 minutes.
9. Made several stops in E mode and did NOT feel any shift until it went from 2nd to 3rd gear.
10. Changed to Sport mode to start in 1st gear. Tranny holds in first much longer than it did when starting in E mode with a cold engine.
I am convinced that the transmission does indeed start in 1st gear when cold and in E mode.
Would welcome others to chime in.
Thread Starter
MBWorld Fanatic!
Joined: Dec 2015
Posts: 1,633
Likes: 520
From: Hagerstown MD
2015 SL400; 2019 X5M40i
Banned
Joined: Nov 2025
Posts: 477
Likes: 187
From: US
Mercedes SL R231
@rmorin49 I think you jinxed me. I am now feeling a little skip in changing gears before the tranny is up to operating temperatures. Even though it wasn't terribly cold today, I did see a momentary rev when changing gears. Once the tranny was warmed up, everything was back to normal. I will watch closely the next time I take the car out.
Thread Starter
MBWorld Fanatic!
Joined: Dec 2015
Posts: 1,633
Likes: 520
From: Hagerstown MD
2015 SL400; 2019 X5M40i
@rmorin49 I think you jinxed me. I am now feeling a little skip in changing gears before the tranny is up to operating temperatures. Even though it wasn't terribly cold today, I did see a momentary rev when changing gears. Once the tranny was warmed up, everything was back to normal. I will watch closely the next time I take the car out.
Banned
Joined: Nov 2025
Posts: 477
Likes: 187
From: US
Mercedes SL R231
I continue to drive mine pretty regularly throughout the year. But I am retired and don’t drive the car long distances on a daily basis. I do believe this transmission behavior is temperature related. I just turned 60,000 miles on the car, but the transmission was serviced two years ago at 43,000 miles. I’ve not noticed it before because I wasn’t watching for it. Now it will be like the song you can’t get out of your head.
🎵BabyShark, do do do do do do BabyShark, do do do do do do BabyShark, do do do do do do BabyShark...🎵
🎵BabyShark, do do do do do do BabyShark, do do do do do do BabyShark, do do do do do do BabyShark...🎵
Thread Starter
MBWorld Fanatic!
Joined: Dec 2015
Posts: 1,633
Likes: 520
From: Hagerstown MD
2015 SL400; 2019 X5M40i
I'm headed out out tonight for a drive. Pretty cold so I'll see how the tranny performs.
Added:
Just returned from a 30 mile ride to get hot fudge sundaes. Transmission performed perfectly. Let the car idle in driveway until idle speed dropped below 1k. Drove off slowly down our alley. First couple of shifts were a little rough but after about 5 minutes all shifts were smooth and uneventful. All is well.
Added:
Just returned from a 30 mile ride to get hot fudge sundaes. Transmission performed perfectly. Let the car idle in driveway until idle speed dropped below 1k. Drove off slowly down our alley. First couple of shifts were a little rough but after about 5 minutes all shifts were smooth and uneventful. All is well.
Last edited by rmorin49; Nov 23, 2025 at 08:41 PM.
MBWorld Fanatic!
Joined: Jan 2009
Posts: 3,820
Likes: 584
From: NY & FL
MB’s of all kinds.
I'm headed out out tonight for a drive. Pretty cold so I'll see how the tranny performs.
Added:
Just returned from a 30 mile ride to get hot fudge sundaes. Transmission performed perfectly. Let the car idle in driveway until idle speed dropped below 1k. Drove off slowly down our alley. First couple of shifts were a little rough but after about 5 minutes all shifts were smooth and uneventful. All is well.
Added:
Just returned from a 30 mile ride to get hot fudge sundaes. Transmission performed perfectly. Let the car idle in driveway until idle speed dropped below 1k. Drove off slowly down our alley. First couple of shifts were a little rough but after about 5 minutes all shifts were smooth and uneventful. All is well.
Sounds 100% normal for a cold car. Hope the sundaes were tasty!
