RaidersR1

Had oil changed around 60k. Got 62k on the odometer. Just put in quart and a half of oil in that period of time. Seems a lot for me. I have done some "spirited" driving in that time plus a couple of 2 hour drives.

Read about the AOS and other issues that tend to show oil usage. I reset my tripometer to 0 at time of oil added. Curious to see how many miles I get and how much oil I'm adding.

Anyone else seen this? Should I look into the AOS?

Car is 07 4S.

jchapura

Can you build a cheapy water manometer and measure the crankcase vacuum?

LexVan

You consumption is high, but not out of spec per Porsche. Porsche says 1 litre per 800 km.

RaidersR1

I'm going to see how it goes going forward and post results. Every 100 miles I'm going to measure.

Petza914

On a 997.1 car, check it first thing in the morning every day before starting the car for the first time. If you see a reading that's a full line down (not the half line at the top of the gauge), confirm it's the same the next day and maybe the 3rd day again, before adding anything. The gauge isn't that accurate and adding oil due to a 1 line down reading one day can result in an overfill condition the next. When you do add oil, if 1 line down, only add 1/4 quart at a time. If 2 lines down, you can add .4 qts. Let it get all the way down and take another reading. If you have to start the car to leave, don't do anything further about oil adjustments until you've taken a new morning reading the next day.

If going on a long trip with what your consumption looks like, you may have to modify this protocol accordingly to make sure you don't run the engine low on oil. Short trips can also result in erroneous readings as the water vapor that builds up won't burn off and will give you a false high oil reading.

With these cars, being 1-2 lines down is better than being overfull (bars all the way to the top).

RaidersR1

Checked oil after 1 day of sitting. 220 miles driven and I have dropped 1 line on the gauge. Reading was done after last trip which was to SF.

So after filling up with oil to full mark, driven 229 miles, down 1 line already. This seems a lot to me. Not my DD so car has sat for two days, checked again yesterday cold and still at second line.

Any thoughts?

ChicagoSpeed996

I think you don't have enough data to be making any presumptive statements. Measure the same place (level), same temperature, either cold or hot (preferably hot because that is what the manual tells you to do) and get a good data set as others have indicated.

semicycler

The simple AOS test is to remove the oil cap while the car is idling. A failing AOS creates a excessive crankcase vacuum which makes removing the oil cap really difficult.

SAN997

Does it always fail with that sign? In other words, if I test the crankcase vacuum, and it is good, does it mean (with very high odds) that the AOS is good?

semicycler

More like the other way around. If the crankcase vacuum is high it can only be from the AOS. So a high crankcase vacuum level can only mean a bad AOS.

A normal AOS reads 4.0 to 6.0 in.W.C. with a manometer connected to the oil cap, preferably 5.0 in.W.C. and corrected for altitude (reads differently in Atlanta than Denver). If your vacuum levels are in the normal range than it's likely the AOS is fine. On the higher side but still in spec? Could be failing but technically still fine. If you can tell the oil cap is hard to remove while idling then odds are the AOS is failing - get it diagnosed further with a proper reading.

Macster

If you can check the oil level with the engine cold and after having sat unused for a while -- hours as in overnight -- the level will be down. The oil is cold.

Depending upon the temperature the level can be down one maybe 2 lines.

If you add oil when the engine is cold and bring the level up then the engine will be overfilled with oil when the engine/oil get up to temperature and this can accelerate oil usage. The oil gets "used" via the AOS. Too much oil can result in more oil vapor being created than normal and more oil vapor means the AOS can pass more vapor to the engine where the oil vapor is burned.

To avoid overfilling the engine check the oil hot and after the engine has been up to temperature a while. A good time to check the oil is after having filled up the gas tank (provided the engine was hot). The gas station drive is probably pretty level and the filling process allows the engine oil some time to drain the sump so you get an more accurate reading of the oil level.

On road trips I check the oil level in my car engine at every fuel stop and depending upon the trip this can be 1 to 2 or even 3 times in a day and anywhere from 250/300 miles to nearly 1000 miles. One can get a sense of oil usage over that long of a distance driven vs. a relatively short time.

RaidersR1

Lots of good info. I'm leaning to the AOS. Will try the oil cap test tonight and see where that goes.

Some the car has been sitting I will start the car and let it get up to temp and then try the test.

Driving to Sacramento Saturday which is an hour away from home. I will check oil before and when I get there.

I think having driven only 200 miles and the oil had dropped down one line, that appears to be excessive. 500 miles I would be ok with that. But 200 and most of that was highway!!

ADias

Lots of cars running around with a lot of water in the oil... do not add oil until it gets down to the lower mark.

RaidersR1

Ok. Understand. This usage has me concerned.

RaidersR1

Ok. THANKS ALL FOR POINTING OUT WHAT I DID WRONG.

Went to the pool store to get chemicals. Drove calmly and let temp get up to operating temp.

It's hot as hell today so that wasn't an issue. Got back home and let the car sit for a few minutes. Did an oil check. Oil is at FULL level hot!! It appears I overfilled it!! Checking cold was NOT the way to go and that's on me.

So now I will always check warm and only add when it's down to the fill level. I bet this will lessen the usage over a bit of time as I properly fill the sump.

THANKS ALL again. The info her is so helpful!!!

😊