C5 Preventative Maintenance Question
Thread Starter
6th Gear
Joined: Nov 2025
Posts: 8
Likes: 0
C5 Preventative Maintenance Question
Hey all, I recently purchased a 99’ Auto C5 with 98K miles. I’m a college student, and I daily drive the car probably 200 miles a week. As it gets closer to crossing 100K, I wanted to know what maintenance you guys would recommend to prevent catastrophe. I bought the car with a decent maintenance record, I’ll leave a short list here of new parts from the last 2 years(some replacements were me, some were previous owner). Also I thankfully do not have the EBCM issue but I’m aware of the repair problem with my year model. Thank you guys for taking the time to read!
Serpentine Belt
AC Belt
Water Pump
Upper Radiator Hose
Idler Pulley
Harmonic Balancer
4 Tires
4 Rotors+pads
Driver side Window Regulator
Knock Sensors+harness(this is the next job on the list)
Serpentine Belt
AC Belt
Water Pump
Upper Radiator Hose
Idler Pulley
Harmonic Balancer
4 Tires
4 Rotors+pads
Driver side Window Regulator
Knock Sensors+harness(this is the next job on the list)
Last edited by stone01; Nov 24, 2025 at 03:49 PM.
Burning Brakes
Joined: Aug 2004
Posts: 1,174
Likes: 125
From: Dunstable MA
St. Jude Donor '05
The fluids have a limited service life. At almost 100K, you want to replace all that you don't have evidence of having already been replaced. Coolant, brake fluid, power steering fluid, ATF (if automatic) and differential. There are lots of threads and YouTube videos on how to get this work done.
Check the Stickies. There's more, but the fluids will keep you busy for a while.
Good luck with your new-to-you C5.
Check the Stickies. There's more, but the fluids will keep you busy for a while.
Good luck with your new-to-you C5.
Administrator
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Moved to C5 Tech.
Advanced
Joined: Jul 2023
Posts: 87
Likes: 22
From: SW CO
Here is another agreement for flushing/changing all fluids.
You don't indicate if you do your own work. If you choose to have a shop flush your brake fluid, ensure they know you want the fluid flushed [with at least a liter of fluid] and not just the brakes bled.
The clutch hydraulics have a separate brake-fluid reservoir. If you don't have a remote bleeder for the clutch slave, consider installing one.
You don't indicate if you do your own work. If you choose to have a shop flush your brake fluid, ensure they know you want the fluid flushed [with at least a liter of fluid] and not just the brakes bled.
The clutch hydraulics have a separate brake-fluid reservoir. If you don't have a remote bleeder for the clutch slave, consider installing one.
Le Mans Master
Joined: Jul 2010
Posts: 5,987
Likes: 719
Hey all, I recently purchased a 99’ C5 with 98K miles. I’m a college student, and I daily drive the car probably 200 miles a week. As it gets closer to crossing 100K, I wanted to know what maintenance you guys would recommend to prevent catastrophe. I bought the car with a decent maintenance record, I’ll leave a short list here of new parts from the last 2 years(some replacements were me, some were previous owner). Also I thankfully do not have the EBCM issue but I’m aware of the repair problem with my year model. Thank you guys for taking the time to read!
Serpentine Belt
AC Belt
Water Pump
Upper Radiator Hose
Idler Pulley
Harmonic Balancer
4 Tires
4 Rotors+pads
Driver side Window Regulator
Knock Sensors+harness(this is the next job on the list)
Serpentine Belt
AC Belt
Water Pump
Upper Radiator Hose
Idler Pulley
Harmonic Balancer
4 Tires
4 Rotors+pads
Driver side Window Regulator
Knock Sensors+harness(this is the next job on the list)
Do you have a backup car??
Thread Starter
6th Gear
Joined: Nov 2025
Posts: 8
Likes: 0
Thread Starter
6th Gear
Joined: Nov 2025
Posts: 8
Likes: 0
Here is another agreement for flushing/changing all fluids.
You don't indicate if you do your own work. If you choose to have a shop flush your brake fluid, ensure they know you want the fluid flushed [with at least a liter of fluid] and not just the brakes bled.
The clutch hydraulics have a separate brake-fluid reservoir. If you don't have a remote bleeder for the clutch slave, consider installing one.
You don't indicate if you do your own work. If you choose to have a shop flush your brake fluid, ensure they know you want the fluid flushed [with at least a liter of fluid] and not just the brakes bled.
The clutch hydraulics have a separate brake-fluid reservoir. If you don't have a remote bleeder for the clutch slave, consider installing one.
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Thread Starter
6th Gear
Joined: Nov 2025
Posts: 8
Likes: 0
The fluids have a limited service life. At almost 100K, you want to replace all that you don't have evidence of having already been replaced. Coolant, brake fluid, power steering fluid, ATF (if automatic) and differential. There are lots of threads and YouTube videos on how to get this work done.
Check the Stickies. There's more, but the fluids will keep you busy for a while.
Good luck with your new-to-you C5.
Check the Stickies. There's more, but the fluids will keep you busy for a while.
Good luck with your new-to-you C5.
Advanced
Joined: Jul 2023
Posts: 87
Likes: 22
From: SW CO
In the auto-repair industry, many techs will advise not messing with the ATF at 100k if there is no service history of prior changes. How did your mechanic determine that the fluid is "still good"?
Tech Contributor
Joined: Jan 2007
Posts: 19,362
Likes: 1,128
From: Dyer, IN
I don't see that you indicated whether your trans is manual or automatic. Your concern re transmission slipping or other problems after a fluid change makes me think it is an automatic.
In the auto-repair industry, many techs will advise not messing with the ATF at 100k if there is no service history of prior changes. How did your mechanic determine that the fluid is "still good"?
In the auto-repair industry, many techs will advise not messing with the ATF at 100k if there is no service history of prior changes. How did your mechanic determine that the fluid is "still good"?
Thread Starter
6th Gear
Joined: Nov 2025
Posts: 8
Likes: 0
I don't see that you indicated whether your trans is manual or automatic. Your concern re transmission slipping or other problems after a fluid change makes me think it is an automatic.
In the auto-repair industry, many techs will advise not messing with the ATF at 100k if there is no service history of prior changes. How did your mechanic determine that the fluid is "still good"?
In the auto-repair industry, many techs will advise not messing with the ATF at 100k if there is no service history of prior changes. How did your mechanic determine that the fluid is "still good"?
Thread Starter
6th Gear
Joined: Nov 2025
Posts: 8
Likes: 0
I don't see that you indicated whether your trans is manual or automatic. Your concern re transmission slipping or other problems after a fluid change makes me think it is an automatic.
In the auto-repair industry, many techs will advise not messing with the ATF at 100k if there is no service history of prior changes. How did your mechanic determine that the fluid is "still good"?
In the auto-repair industry, many techs will advise not messing with the ATF at 100k if there is no service history of prior changes. How did your mechanic determine that the fluid is "still good"?
Running Guns & Moonshine
Joined: Aug 2001
Posts: 12,505
Likes: 7,186
From: CT
I think the great thing is how generally durable these cars are. You've hit a lot of the common ones already. The fluid advice is certainly fair. Just keep good and FRESH all-seasons on it and it will treat you well. Be extra cautious if you're anywhere with snow / ice. There are some days when Uber should be the answer.
Tech Contributor
Joined: Jan 2007
Posts: 19,362
Likes: 1,128
From: Dyer, IN
I would still change the filter/fluid to establish a baseline of ownership. Again, do not power flush.
Race Director
Joined: Oct 2004
Posts: 12,859
Likes: 4,658
As a 2000 A4 C5 owner for the last 22 years, with an all original 4L60E with 150,000 miles on it, I feel I can reply here with some basic knowledge and common sense. My last 2 vehicles before my C5 were a 2003 Buick LeSabre with 400,000 miles on it with original trans, and a 1995 Jeep Grand Cherokee with 350,000 miles on it. Trans shops told me once a vehicle gets over 75,000-80,000 miles on it, NEVER flush the trans. Just drain the fluid and install a new filter. When my C5 hit 100,000 miles, I changed the trans fluid and filter. I've had 2 600+hp 427s yanking on that trans. As Lucky, AND I are saying, just change out your fluid and filter, and DO NOT FLUSH IT!! As far as the fluid being red, mine was also a nice red at 100,000 miles. Doesn't mean it had the same lubricity as it did at 40,000 miles. Blood is red too, but would probably not work well! Sure, being red beats a brownish, burnt smelling fluid. But it means little more than that. Oh, and if you tune the car, DO NOT let the tuner remove Torque Management. Raise the value. Mine was set at 450lb/ft from GM, IIRC. Tuner raised it to 1,000lb/ft. I don't know what else he did, but the results speak for themselves....
Advanced
Joined: Jul 2023
Posts: 87
Likes: 22
From: SW CO