Maintenance Questions
Thread Starter
Heel & Toe
Joined: Jun 2024
Posts: 17
Likes: 12
Maintenance Questions
I am the new owner of a new to me 2021 C8 HTC Z51. When purchased last week the car had 1,680 miles on the clock and as of today it has almost 1,725. I am going to be scheduling service next week for an oil change only because I do not know for sure when the last change was done, I know this needs to be done yearly regardless of miles. My question to the experts is are there any other services I should have them do while the car is there?
Popular Reply
Jun 14, 2024, 09:11 AM
Race Director
Joined: Mar 2007
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The requirements for the motor oil and oil filter are:
change when you get a change oil soon message, or change at least once a year whichever is first.
For the DCT external canister filter:
change between 7000-8000 miles, regardless of if change earlier, then at 22,500 miles, then every 22,500 miles after. or every 24 hours of track use. Other than that, there is no time limit on the filter, it is not necessary to change it right now with your mileage (unless it was tracked maybe). Change if you want to.
For the transmission fluid:
Change when you get the change fluid soon message, or 3 years from the last time (in your case in service date), or 45000 miles. Or every 24 hours of track use. I recommend changing the fluid.
It is not necessary to change the DCT external canister filter at the same time as the transmission fluid (and I did not) because they are on separate schedules, unless the triggers are coincident. Change both if you want to. But you still need to change the filter again between 7000-8000 miles.
change when you get a change oil soon message, or change at least once a year whichever is first.
For the DCT external canister filter:
change between 7000-8000 miles, regardless of if change earlier, then at 22,500 miles, then every 22,500 miles after. or every 24 hours of track use. Other than that, there is no time limit on the filter, it is not necessary to change it right now with your mileage (unless it was tracked maybe). Change if you want to.
For the transmission fluid:
Change when you get the change fluid soon message, or 3 years from the last time (in your case in service date), or 45000 miles. Or every 24 hours of track use. I recommend changing the fluid.
It is not necessary to change the DCT external canister filter at the same time as the transmission fluid (and I did not) because they are on separate schedules, unless the triggers are coincident. Change both if you want to. But you still need to change the filter again between 7000-8000 miles.
CF Community Team
Joined: Nov 2005
Posts: 5,252
Likes: 2,892
From: Charlotte N.C.
Go ahead and also have the DCT fluid and filter changed. Not only so you then know that it was done and when but also to get it documented in the GM system. I recently bought a 2020 with 8800miles and no records and had a local GM do the engine oil and filter and the DCT filter. I did the fluid myself at home. It's expensive, be ready.
Race Director
Joined: Mar 2007
Posts: 11,421
Likes: 8,575
The requirements for the motor oil and oil filter are:
change when you get a change oil soon message, or change at least once a year whichever is first.
For the DCT external canister filter:
change between 7000-8000 miles, regardless of if change earlier, then at 22,500 miles, then every 22,500 miles after. or every 24 hours of track use. Other than that, there is no time limit on the filter, it is not necessary to change it right now with your mileage (unless it was tracked maybe). Change if you want to.
For the transmission fluid:
Change when you get the change fluid soon message, or 3 years from the last time (in your case in service date), or 45000 miles. Or every 24 hours of track use. I recommend changing the fluid.
It is not necessary to change the DCT external canister filter at the same time as the transmission fluid (and I did not) because they are on separate schedules, unless the triggers are coincident. Change both if you want to. But you still need to change the filter again between 7000-8000 miles.
change when you get a change oil soon message, or change at least once a year whichever is first.
For the DCT external canister filter:
change between 7000-8000 miles, regardless of if change earlier, then at 22,500 miles, then every 22,500 miles after. or every 24 hours of track use. Other than that, there is no time limit on the filter, it is not necessary to change it right now with your mileage (unless it was tracked maybe). Change if you want to.
For the transmission fluid:
Change when you get the change fluid soon message, or 3 years from the last time (in your case in service date), or 45000 miles. Or every 24 hours of track use. I recommend changing the fluid.
It is not necessary to change the DCT external canister filter at the same time as the transmission fluid (and I did not) because they are on separate schedules, unless the triggers are coincident. Change both if you want to. But you still need to change the filter again between 7000-8000 miles.
Race Director
Joined: Mar 2007
Posts: 11,421
Likes: 8,575
By the way, what are your oil and fluid life percentages?
Be aware that the oil life monitor takes a bunch of factors into account including time and mileage - and it will time out 1 year after the last change if not sooner. If it was reset properly, by the previous owner, you could rely on that for the oil life left. Or if worried, you could change it.
Be aware that the while the fluid life monitor may take a bunch of factors into account, it appears from my experience (I have a 2021) and forum reports, that it does NOT take time into account, so you must observe the three year requirement regardless of what the FLM says. It it has not been changed since delivery, it is time for a change, regardless of whether its showing you a high percent life remaining.
You do not have a filter life monitor - but its miles only for that anyway. And you are not near the required mileage for that (7000-8000).
Be aware that the oil life monitor takes a bunch of factors into account including time and mileage - and it will time out 1 year after the last change if not sooner. If it was reset properly, by the previous owner, you could rely on that for the oil life left. Or if worried, you could change it.
Be aware that the while the fluid life monitor may take a bunch of factors into account, it appears from my experience (I have a 2021) and forum reports, that it does NOT take time into account, so you must observe the three year requirement regardless of what the FLM says. It it has not been changed since delivery, it is time for a change, regardless of whether its showing you a high percent life remaining.
You do not have a filter life monitor - but its miles only for that anyway. And you are not near the required mileage for that (7000-8000).
Thread Starter
Heel & Toe
Joined: Jun 2024
Posts: 17
Likes: 12
Monitor is at 78%, I am changing the oil regardless just because I have no idea when it was changed last for sure. My questions is more of what else should be changed / checked.
Thanks for all the responses so far.
Thanks for all the responses so far.
Melting Slicks
Joined: May 2021
Posts: 2,562
Likes: 1,579
You should check the oil level when you fuel the car for a couple tanks of gas. Check it with the engine running.
Some C8's consume oil when new for a bit.
Also, since you have a 2021 model, when at the dealer you should ask them to let you inspect the metal shear plate that attaches under the engine craddle. (big aluminum plate). It has to come off to complete the DCT fluid swap service since you are at 3yrs. Don't let them wipe it off before you see it!
Wipe your hand across that plate and look for any sign of oil on it. If it has oil on it (likely very close to clear or honey color), then you need to have DCT checked with tracing powder typically around the middle area of the driver side. There's a porosity issue in that area on some vehicles.
They should check the fill level by opening the inspection plug, and if it's low that is another indicator it needs to be further checked.
Some C8's consume oil when new for a bit.
Also, since you have a 2021 model, when at the dealer you should ask them to let you inspect the metal shear plate that attaches under the engine craddle. (big aluminum plate). It has to come off to complete the DCT fluid swap service since you are at 3yrs. Don't let them wipe it off before you see it!
Wipe your hand across that plate and look for any sign of oil on it. If it has oil on it (likely very close to clear or honey color), then you need to have DCT checked with tracing powder typically around the middle area of the driver side. There's a porosity issue in that area on some vehicles.
They should check the fill level by opening the inspection plug, and if it's low that is another indicator it needs to be further checked.
Last edited by dohabandit; Jun 14, 2024 at 11:41 AM.
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CF Community Team
Joined: Nov 2005
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From: Charlotte N.C.
Thread Starter
Heel & Toe
Joined: Jun 2024
Posts: 17
Likes: 12
Thanks all