Is my (5V BW) oil consumption reasonable or concerning?

[Midcont]

I had my oil changed at just over 20k miles in Oct '25 and the car sat most of the winter.
At the end of March '26 with 21,610 miles it asked me for a quart of oil which I added.
A few days ago, end of April '26 with 21959 miles it asked me for another quart of oil.

This is the second time this sequence has happened in about the same time frame/miles.
It was changed in Oct. at the dealer after I expressed my concerns about what I had experienced.
They told me to watch and report back...now that dealership is being sold and there is no continuity in the service department.
Is this a concern? If so what should my next steps be?
The car was carefully broken in and always properly warmed up.

 

[dribs15]

Leaking vs burning... My guess is the former.
Bring it back in ASAP. Also, do you have another dealer in your area that you can get a second opinion from (if needed)?

 

[Finally-a-V]

Am I reading this correctly? You added a quart in 1600 miles? That's probably alright...BUT you added another quart in 340 miles??? I'd say that isn't right. I have never added any oil to mine. I have 10K miles, and it's changed annually.

 

[1Evil55]

I'd search for a larger dealer near you. Unless you found a puddle under the parked car, you're burning it and shouldn't be.

 

[jbawden]

I guess I would start with making sure the proper amount was installed in the first place. There are myriad underfill stories floating around here over the years. Flat level ground and let it sit overnight is where I would start. 1qt in 350 miles is extreme.

 

[Midcont]

I guess I would start with making sure the proper amount was installed in the first place. There are myriad underfill stories floating around here over the years. Flat level ground and let it sit overnight is where I would start. 1qt in 350 miles is extreme.

This is why I had the last oil change at the dealership, with their understanding I had just had this issue. This was so they had control over the oil change. Now I guess I'm going to have to do this process all over again.

 

[vagabond]

Some oil consumption is expected if running the engine hard (e.g. track use).

That said, I typically had some oil smell after oil changes. My oil consumption picked up over time (>1 quart every 4-5000 miles of normal driving) and I came out to a few drops of oil the other day. I took it to the dealership and they found the displacement on demand (DOD) aka cylinder deactivation aka active fuel management (AFM) oil plug was leaking in the driver side head. Manual CT5-V Blackwing LT4s don't have the AFM system and instead have a plug installed. Missing O-ring since it was built (it has 26000 miles now). Oil leaking in the valve area making its way out behind the block and down to the oil pan.

 

[Midcont]

Some oil consumption is expected if running the engine hard (e.g. track use).

That said, I typically had some oil smell after oil changes. My oil consumption picked up over time (>1 quart every 4-5000 miles of normal driving) and I came out to a few drops of oil the other day. I took it to the dealership and they found the displacement on demand (DOD) aka cylinder deactivation aka active fuel management (AFM) oil plug was leaking in the driver side head. Manual CT5-V Blackwing LT4s don't have the AFM system and instead have a plug installed. Missing O-ring since it was built (it has 26000 miles now). Oil leaking in the valve area making its way out behind the block and down to the oil pan.

No oil detected on floor of garage ever.

 

[jbawden]

Dealership doesn't necessarily equal competence. I understand that you need to start there to build a warranty trend, but I would still confirm the level with the dipstick and create your own baseline.

 

[schernov]

Engine Oil Consumption Guidelines – TechLink

gm-techlink.com

 

[BW56M]

Dealership doesn't necessarily equal competence. I understand that you need to start there to build a warranty trend, but I would still confirm the level with the dipstick and create your own baseline.

I agree 100%. I would also check with the dealer as to what oil they actually used. I believe there has been claims that some dealers have used the same bulk oil that they put in almost everything.

 

[NorCal Blackwing]

I had no oil consumption issues until fairly recently, then at around 20K mileage I was suddenly going from a full fill to the low oil warning every ~ 1000 miles. I'd go in every few weeks to get the oil level reset and checked at a local dealer - x3 tries with a pretty consistent rate of oil loss. I'd bring my own oil and check the fill myself, but it was necessary for them to do it and note the levels/intervals as part of the consumption monitoring.

They didn't see any signs of a leak, and it was just within the acceptable range for a street driven car, per GM guidelines. Any potential further investigation would have apparently involved a tear-down which didn't seem that appealing.

The car was meticulously broken in and while driven spiritedly on backroads, no track, and no banging off the rev limiter.

 

[CB34]

I had no oil consumption issues until fairly recently, then at around 20K mileage I was suddenly going from a full fill to the low oil warning every ~ 1000 miles. I'd go in every few weeks to get the oil level reset and checked at a local dealer - x3 tries with a pretty consistent rate of oil loss. I'd bring my own oil and check the fill myself, but it was necessary for them to do it and note the levels/intervals as part of the consumption monitoring.

They didn't see any signs of a leak, and it was just within the acceptable range for a street driven car, per GM guidelines. Any potential further investigation would have involved a tear-down which didn't seem that appealing.

The car was meticulously broken in and while driven spiritedly on backroads, no track, and no banging off the rev limiter.

You should get that checked before your warranty expires. That's not normal.

 

[NorCal Blackwing]

You should get that checked before your warranty expires. That's not normal.

Unfortunately this car's no longer my problem

 

[hmrh]

Unfortunately this car's no longer my problem

Are you enjoying the Carrera T? They seem lovely

 

[NorCal Blackwing]

Are you enjoying the Carrera T? They seem lovely

Oh definitely. I got it back in 2019 new off the lot - it's the sports car I've kept the longest, and it'll be the last one I'll sell. For my use case (very early AM backroads in the mountains around here) it's perfect; about the right amount of power to have fun without engaging in felonies, wheel control and suspension that eats up our lumpy backroads without getting floaty, and an amazing chassis that can do absurd things on tight technical roads.

It's a very different experience from the Blackwing. I absolutely loved the V8 character and torque of the Blackwing, and in its way it was more interesting and thrilling to drive fast on those same backroads. If you combine it with the added 'sleeper' effect and practicality, and of course the delightful six-speed manual (compared to the 7-speed in the T), oh man ... the Blackwing is a generationally great car.

I would have kept both if I could, but when it came time to trim down to one 'fun' car - even with my thirsty engine with a slice of possible catastrophic failure, it was still a really tough choice.

 

[jbawden]

Well dang @NorCal Blackwing I guess one less north bay BW. Sorry you had to let it go, but maybe I'll see you at Turtle Rock in the Carrera.