Cadillac Owners Forum banner
1 - 13 of 13 Posts

·
Registered
2017 XT5 Platinum, Dark Adriatic Blue Metalic, Maple Sugar
Joined
·
383 Posts
Discussion Starter · #1 ·
My 2017 is at 55,000 miles. I thought it might be near time to change the ATF. I checked the manual and it states every 45,000 miles for "Severe" use, but doesn't give any time for "Normal" use. I consider myself a "Normal" user. Does this mean my ATF never needs to be changed?
 

·
Registered
2020 XT5 Platinum in Red Horizon Tintcoat and Maple Sugar interior
Joined
·
770 Posts
I've never changed the transmission fluid in any car I've ever owned. My XTS had 100K+ miles on it when I traded it for my XT5 and shifted fine.
 

·
Registered
2011 CTS4 Coupe, 2014 ELR, 2018 XT5 AWD
Joined
·
1,274 Posts
45000 is for severe use. Lifetime for normal use.
If you want to change it, change it now. Changing it at higher miles (75000-100000) can be worse than not changing it at all. Also, no transmission flushing. Just drain and refill.
 

·
Registered
2017 XT5
Joined
·
1,037 Posts
When an automobile manufacturer says a fluid is "good for a lifetime" it means "the lifetime of the factory warranty". Based on my mechanical experience, I would suggest a change at every 50K miles (+/- 10K) would be best. The idea that original fluid should not be changed at high (80K+) mileage is something of an old wives tale (or "urban legend" for those that prefer a more PC term). Today's modern friction materials don't degrade like your daddy's 1960's Oldsmobile.
 

·
Registered
2011 CTS4 Coupe, 2014 ELR, 2018 XT5 AWD
Joined
·
1,274 Posts
When an automobile manufacturer says a fluid is "good for a lifetime" it means "the lifetime of the factory warranty". Based on my mechanical experience, I would suggest a change at every 50K miles (+/- 10K) would be best. The idea that original fluid should not be changed at high (80K+) mileage is something of an old wives tale (or "urban legend" for those that prefer a more PC term). Today's modern friction materials don't degrade like your daddy's 1960's Oldsmobile.
I didn't add the high milage trans fluid part because of an urban legend.
I added it because of direct experience.
A fliud change at 105000 cost me a transmission rebuild on a 1998 Olds.

But you do you.
 

·
Registered
2019 CT6-V
Joined
·
75 Posts
The commonly-given reason for advising against high-mileage transmission fluid changes is detergent. ATF contains detergent additives to keep particles suspended (where they can be trapped by the filters). In an older trans with a lot of varnish buildup, and not much detergent still active in the fluid, new fluid with the full detergent additive package can break loose all that old varnish and plug a new filter, causing clutch slip and burning up the trans. How often this happens? Who knows, but based on CSIMME01's experience, it's not unheard of. I have changed high-mileage fluid and not had this problem, but I guess some might see it as a roll of the dice.
 

·
Registered
2011 CTS4 Coupe, 2014 ELR, 2018 XT5 AWD
Joined
·
1,274 Posts
The commonly-given reason for advising against high-mileage transmission fluid changes is detergent. ATF contains detergent additives to keep particles suspended (where they can be trapped by the filters). In an older trans with a lot of varnish buildup, and not much detergent still active in the fluid, new fluid with the full detergent additive package can break loose all that old varnish and plug a new filter, causing clutch slip and burning up the trans. How often this happens? Who knows, but based on CSIMME01's experience, it's not unheard of. I have changed high-mileage fluid and not had this problem, but I guess some might see it as a roll of the dice.
I my case the fluid change disturbed/broke free enough material that the pressure control valve in the transmission was contaminated. This caused shutter at low speeds and slippage during high torque shifts.
 

·
Registered
2020 XT5 Platinum in Red Horizon Tintcoat and Maple Sugar interior
Joined
·
770 Posts
My 2017 is at 55,000 miles. I thought it might be near time to change the ATF. I checked the manual and it states every 45,000 miles for "Severe" use, but doesn't give any time for "Normal" use. I consider myself a "Normal" user. Does this mean my ATF never needs to be changed?
I would say if you are a "Normal" user and the transmission is operating fine then forget about it and leave well enough alone. If a service interval isn't listed on the maintenance chart there must be a reason. That's what I would go by but of course there are people out there who still change their oil every 3K miles while I just go by the oil life monitor. To each his own I guess.
 

·
Registered
2019 XTS PremLux, 2020 XT5 Premlux
Joined
·
290 Posts
I did some research on this awhile ago and found if you wait too long/many miles to change trans fluid it's best to leave it because as CSIMME01 mentioned the new fluid will dislodge particles and disrupt the transmission. It's best to do no more than every 40-50k miles.
When I had my 2014 Malibu I did it at 45k and I could feel it shifted better, smoother. That said, once you start its good to keep changing every 40-50k. Anyway that's what I found in fact I'm bringing my 2020 Ranger in next week to change it's trans fluid it's at 51k.
 

·
Registered
2018 XT5
Joined
·
67 Posts
I did some research on this awhile ago and found if you wait too long/many miles to change trans fluid it's best to leave it because as CSIMME01 mentioned the new fluid will dislodge particles and disrupt the transmission. It's best to do no more than every 40-50k miles.
When I had my 2014 Malibu I did it at 45k and I could feel it shifted better, smoother. That said, once you start its good to keep changing every 40-50k. Anyway that's what I found in fact I'm bringing my 2020 Ranger in next week to change it's trans fluid it's at 51k.
I agree. I feel comfortable with changing it at approx. every 50K miles or leave it alone.
 

·
Registered
2017 XT5
Joined
·
1,037 Posts
New fluid in an old "modern" transmission does not to really "dislodge particles". What happens is that the clutches wear and their friction material becomes suspended in the fluid. When you change the fluid, that suspended friction material is now gone, and the clutches themselves, having worn, are less able to lock together. The new fluid can let those clutches slip and then you have problems. There are some solutions for this. One is to use a higher viscosity oil. Another is to use an anti-slip additive such as that made by Liqui-Moly. But honestly, if the clutches are that worn, the transmission likely would not have lasted much longer with the old fluid anyhow. Another comment is that the definition of "high mileage" is quite different today that it was in cars 15 years ago and older. I remember when a car with 100K miles was a piece of crap ready for the junk heap. Today, we have even basic "appliance" cars on the road with 200K going strong.
 

·
Registered
2011 CTS4 Coupe, 2014 ELR, 2018 XT5 AWD
Joined
·
1,274 Posts
New fluid in an old "modern" transmission does not to really "dislodge particles". What happens is that the clutches wear and their friction material becomes suspended in the fluid. When you change the fluid, that suspended friction material is now gone, and the clutches themselves, having worn, are less able to lock together. The new fluid can let those clutches slip and then you have problems. There are some solutions for this. One is to use a higher viscosity oil. Another is to use an anti-slip additive such as that made by Liqui-Moly. But honestly, if the clutches are that worn, the transmission likely would not have lasted much longer with the old fluid anyhow. Another comment is that the definition of "high mileage" is quite different today that it was in cars 15 years ago and older. I remember when a car with 100K miles was a piece of crap ready for the junk heap. Today, we have even basic "appliance" cars on the road with 200K going strong.
In the real world a fluid change on my 100k 1998 Olds Intriugue lead to a contaminated Pressure Control Solenoid that killed the transmission. It was running perfectly before the fluid change. Afterwords it shuddered on take off and slipped when shifting at high torque.
I repeat.
Drove into the shop driving perfectly.
Drove out of the shop with serious problems.
Literally, the first time I put it in gear after the fluid change it shuddered. The crap that "broke loose" during the fluid change contaminated the sealing surfaces of the Pc Valve that prevented the transmission from property controlling the clutch pressures. That caused poor low speed clutch engagement and clutch slipping at high torque. A week later this car with fresh, bright red trans fluid, needed a transmission rebuild because the slipping clutches self destructed.destruction.
 

·
Registered
2020 XT5 Platinum in Red Horizon Tintcoat and Maple Sugar interior
Joined
·
770 Posts
Easy to say now of course but if something is running perfectly I think I would have just left well enough alone and let it continue to run perfectly, especially when it's known that changing the fluid at that mileage carries risks.
 
1 - 13 of 13 Posts
Top