Update - So I've had the car out for a few weeks and I've managed to put 2,500 Kms on it since the last oil change in late September, about a month before I put the car away. Just checked the oil and it was down below the recommended level. I added one quart and it brought the level back up to just below the middle of the hash mark area on the dip stick. So it looks like consumption is about 1qt per 2,500Km, which is an improvement over what looked like 1qt per 1500KM. Now, I'm currently being a lot more careful to measure and look at the kms and oil amount I'm adding in so that I get a real precise measurement. The dealer had told me to go in and get the oil added at the dealership so that they could track the consumption. But besides this being a pain, I want to have a really good idea of what is happening before they tell me what they see. With the warranty at 5yrs and 150,000KM I'm not in too much of a rush to let them go tearing into the engine before I understand the severity of the issue. Besides, I suspect that this level of consumption is probably within GM's specs, even if it sounds high for most drivers. I understand from a member at the US forum, that GM has a bulletin out recommending that cars with high oil consumption have their valves replaced. He had this repair done and his consumption is now 1/4-1/2 quart per 1000 mi (or 1qt per 2000Km) which GM claims is within spec. So, it looks like I would fall within that threshold anyway and would be facing an uphill battle for any redress.
I would be interested to know from those of you with more engine knowledge if there are reasons why consumption would decrease over time (since usually the opposite is more likely). Thanks.
Oil consumption varies from engine to engine as you know......I believe you to be correct when you say that your engine's consumption is within GM's specs.-- Whether yours is excessive or not is a matter of opinion.......As we all know there is always some consumption -- most of which is not noticeable -- but engines vary somewhat causing increased consumption. GM's guidelines are what? : consumption in excess of a quart/liter in 1500km warrants repair?
I think you've hit the nail on the head saying that your consumption isn't excessive at the moment (pending final confirmation) ....... and that you need to calculate consumption closely now at least to get a baseline. The dealer will want to be involved in this process and if it were me I'd let them be involved.-- probably a requirement from GM.
That way if consumption worsens (or improves) then you'll know about it quickly.
As to whether consumption on a new engine may improve with age -- I would say it might as the engine parts such as rings and valves 'seat in' properly which can take a few thousand kilometers.
If it were my car I'd watch the oil level closely just as you are doing.......allow the dealer to fill or maintain your oil and monitor for any consumption to determine the exact issue.
BTW -- to my mind the level "just below the middle of the hash marks" is down perhaps half a liter (at least on other vehicles I've owned)....so you may want to fill to the top of the hash marks to get benefit of a 'full crankcase'.
Be careful to not overfill tho. This apparently can cause foaming which then gets pumped into the oiling system.
I find checking levels the morning after using the car and topping up as needed then. That way all the oil has had a chance to drain back into the crankcase. Be sure the garage is level.
I does sound like GM is aware of the issues and is prepared to help should your engine consume excessively.
There will be other tests involved with their evaluation such as cylinder compression (wet and dry) to help them diagnose the problem.
The "soot" you mentioned is probably an accumulation from slow(er) in-town type driving. It should disappear when the car is driven on a long trip steady speed. -- and yes as Keith mentioned b4: don't be afraid to make the engine 'work' -- that's what they're built for.
I would avoid excessive 'red-lining' tho as also mentioned.
I would also get that bulletin info you mentioned about. It may be handy if the dealer knows little about the problem. Google could also be your friend if you haven't already.
Keep us apprised and GL.
Colin.
