yashagrawal

1 bar=0.4 L, for the genuine OCD's :-)

Fahrer

My 2008 C2S uses oil at the rate of about quart per 5000 miles. I actually never add oil between changes ( every year/3500 miles). It's a weekend ride/garage queen.

I broke it in "by the book" as I do with all new cars.

Yet anothercrisis

I have added 12 ounces in 10 thousand miles. Oil has been changed twice in that period which of course resets levels to full (if they were down, but not down enough to register on the electronic dipstick). The c2S was bought new in 2012.

Macster

Your tech is right.

It can be perfectly normal for the engine to use a quart in under 1K miles, or to use no oil in 5K miles and anywhere in between. As long as the engine is operating with no untoward behavior, the CEL remains dark, there is no problem.

In the case the engine being reported as using no oil, what you have to consider is it is using oil.

But the accumulation of unburned gasoline and water (mainly water) is making up for the volume of lost oil. Short trips can really have the accumulation of unburned gasoline and water skyrocket, so to speak, in the engine oil.

(As an aside, I had my Boxster's engine oil analyzed shortly after I bought the car new and the water content was 7%. That's over 1/2 quart of water in the oil. My curiosity piqued I did some investigating and found out just how cold blooded these engines are.)

The flip side is the owner goes merrily along until one day he takes a nice long trip. Maybe gives the engine the whip a bit, too, during the trip.

The oil level drops. Sometimes drastically. All of the sudden the engine's an oil burner.

Well, not really.

What happened is the more volatile contaminates (unburned fuel and water) evaporated because the engine oil got nice and hot and remained hot for a while. The sudden drop in the oil level was the result of oil consumption over a number of miles that was highlighted by the loss of the other fluids that had been contaminating the oil.

The above is why I always discount claims of my engine uses no oil in xxxx miles and I am always willing to give the engine the benefit of the doubt when the owner claims the engine is an oil burner.

Also, how one uses the car, the engine, plays a role. Push the engine really hard, hard throttle, high rpms, and the oil consumption can go up, assuming there is no evaporation of unburned fuel and water from the oil. Or let the engine idle a lot, and this too can have oil consumption go up from its "normal" rate.

Last but not least for those engines that truly consume more oil I suspect the real culprit is a sub-par AOS rather than something inherently wrong or off in the engine.

The smoking at start up -- which we all see once in a while -- arises from the AOS and its failure to remove all (or enough) oil vapor from the crankcase fumes it routes to the intake. These fumes contact intake walls and oil condenses and collects. After the engine is shut off this oil warms up as the intake gains heat from the engine and the oil runs down into the engine.

If the AOS is not working right, or as efficiently as it should, it can let too much oil in the form of vapor past and into the intake where it is burned, most of the time the engine is running.

Since the engine is hot and the car moving one won't notice the oil being burned. That is there is none of the smoking one sees at cold engine start. But the engine uses oil, courtesy of the less than efficient AOS.

MessyMarvin

I have had mine for almost a year, I have only done 1 oil change, so far it has not burned any oil. I put about 5k miles on it before the change and it was still full.

sandwedge

About a quart every 2,000 miles. My -06 C4S used no oil at all.

slicky rick

997.2 C2s, 25k km no oil addition in between oil changes. Regular 100km runs with occassional 200plus kph sprints. 4 years by march. But nowadays, takes a minute to measure oil level wherein before it only takes 4 to 5 seconds....something is starting to miss.

gabe2006

997.1 C2 oil changed 3500mi ago and level did not drop since then. I'll change the oil before I need to add anything because it will be one year from last oil change (March).

Dadio

Variables that contribute to oil usage include short trips, multiple start stop cycles, driving style that keeps engine in the higher end of the rev band, etc... Owners manual states up to 1.6 qts per 622 miles is normal. This info can be found at the bottom of pg 328 and is the same for all 997 engines.

Perk10

Macster - awesome post. I forwarded to my tech and he enjoyed reading it.

To everyone else, I am glad to read that this is, in fact, a normal occurrence. I believe I am going through about a half a quart every 1,000-1,200 miles at this point but that is a rough estimate.

myw

that would be in line with me. every 2000 miles need to add almost 1 L

Perk10

Sounds great, Tom!

eljeffo64

My C2S is now almost eight years old, with me for seven years and currently on 42,000 kms - 25k miles; never uses a drop of oil, even after the occasional track day. Still in love after all this time :-)

Fahrer

Another variable may be the accuracy of the system designed to check oil level.

Hatzenbach

Same here