Ls1 oil consumption- Good leakdown/compression?
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Instructor
Joined: Aug 2020
Posts: 203
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Ls1 oil consumption- Good leakdown/compression?
2000 C5 has 157k and uses oil much more than the already high rate GM says is acceptable. Spits black carbon out the exhaust, covers the back of the car and stains the concrete.
I did an LS6 valley pan to try to help and was surprised to see I did not need to grind the boss in the valley to clear so perhaps this car has a later engine and who knows how many miles. I've tried every other option to get this under control and now feel that the only thing left is to re-ring it as per the GM TSB which is obviously a significant job.
But I did a leakdown and compression test and got good numbers on all cylinders, could that be and still need to re-ring?
Also the ring kit in the TSB is discontinued, is there a new recommended ring pack or procedure? The TSB cautions against honing the bores and only replace certain rings but digging this far in I would want to freshen everything up.
I did an LS6 valley pan to try to help and was surprised to see I did not need to grind the boss in the valley to clear so perhaps this car has a later engine and who knows how many miles. I've tried every other option to get this under control and now feel that the only thing left is to re-ring it as per the GM TSB which is obviously a significant job.
But I did a leakdown and compression test and got good numbers on all cylinders, could that be and still need to re-ring?
Also the ring kit in the TSB is discontinued, is there a new recommended ring pack or procedure? The TSB cautions against honing the bores and only replace certain rings but digging this far in I would want to freshen everything up.
Tech Contributor
Joined: Jan 2007
Posts: 19,472
Likes: 1,171
From: Dyer, IN
2000 C5 has 157k and uses oil much more than the already high rate GM says is acceptable. Spits black carbon out the exhaust, covers the back of the car and stains the concrete.
I did an LS6 valley pan to try to help and was surprised to see I did not need to grind the boss in the valley to clear so perhaps this car has a later engine and who knows how many miles. I've tried every other option to get this under control and now feel that the only thing left is to re-ring it as per the GM TSB which is obviously a significant job.
But I did a leakdown and compression test and got good numbers on all cylinders, could that be and still need to re-ring?
Also the ring kit in the TSB is discontinued, is there a new recommended ring pack or procedure? The TSB cautions against honing the bores and only replace certain rings but digging this far in I would want to freshen everything up.
I did an LS6 valley pan to try to help and was surprised to see I did not need to grind the boss in the valley to clear so perhaps this car has a later engine and who knows how many miles. I've tried every other option to get this under control and now feel that the only thing left is to re-ring it as per the GM TSB which is obviously a significant job.
But I did a leakdown and compression test and got good numbers on all cylinders, could that be and still need to re-ring?
Also the ring kit in the TSB is discontinued, is there a new recommended ring pack or procedure? The TSB cautions against honing the bores and only replace certain rings but digging this far in I would want to freshen everything up.
- Are you the original owner?
- Any modifications?
- Any codes?
- Live data you can share?
- Fuel pressure? Engine vacuum?
- Any smoke from the exhaust?
- How much oil do you consume in what amount of time?
Racer
Joined: Apr 2019
Posts: 310
Likes: 120
From: Central PA
2024 C5of the Year Finalist - Unmodified
2000 C5 has 157k and uses oil much more than the already high rate GM says is acceptable. Spits black carbon out the exhaust, covers the back of the car and stains the concrete.
I did an LS6 valley pan to try to help and was surprised to see I did not need to grind the boss in the valley to clear so perhaps this car has a later engine and who knows how many miles.
I did an LS6 valley pan to try to help and was surprised to see I did not need to grind the boss in the valley to clear so perhaps this car has a later engine and who knows how many miles.
Last edited by VETTEYOG; May 26, 2026 at 12:48 PM.
Safety Car
Joined: Mar 2017
Posts: 3,771
Likes: 940
From: Orlando Florida
My thinking exactly. 26 year old elastomers, in a not-so-wonderful environment. Also, which head castings do you have? Unless I've mixed up my readings, a 2000 should be 853's, no?
Last edited by redzg; May 27, 2026 at 05:40 PM.
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When I did the seals I made sure to use sealant on the bolts that go thru the intake. I used permatex non hardening sealer.
The heads are coming off first to be checked out to see if there is anything wrong with them. Maybe the epoxy on the intake ports is loose (although I would expect to see a drastic difference looking at the plugs).
The heads are coming off first to be checked out to see if there is anything wrong with them. Maybe the epoxy on the intake ports is loose (although I would expect to see a drastic difference looking at the plugs).
Safety Car
Joined: Mar 2017
Posts: 3,771
Likes: 940
From: Orlando Florida
Have you checked your VIN vs production dates to see how early/late in the 2000 model year it is? As you note, perhaps you have the later block — which may mean later oil control rings. Not sure of the implications, but it’s always good to know your parameters.
Also, no leaks? Front main, rear main, oil pan, valve covers?
Kind of hate to say it, but I’m crossing my fingers the epoxy needs a re-application.
Also, no leaks? Front main, rear main, oil pan, valve covers?
Kind of hate to say it, but I’m crossing my fingers the epoxy needs a re-application.
Burning Brakes
Joined: Feb 2022
Posts: 897
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From: NW Burbs of Chi-Town
2025 C5 of the Year Finalist - Modified
When I did the seals I made sure to use sealant on the bolts that go thru the intake. I used permatex non hardening sealer.
The heads are coming off first to be checked out to see if there is anything wrong with them. Maybe the epoxy on the intake ports is loose (although I would expect to see a drastic difference looking at the plugs).
The heads are coming off first to be checked out to see if there is anything wrong with them. Maybe the epoxy on the intake ports is loose (although I would expect to see a drastic difference looking at the plugs).