Oil Consumption

My 2006 Cayman S is consuming a lot of oil and Im trying to figure how what's going with it. I had a local shop here in Arizona do a leak down test which had less than 1% loss, bore scope that showed no scoring and AOS test that seems to be within normal range at 4.4. Per the shops advice, we have switched oil from 0W-40 to Redline 5w-50. This oil seems to be the better option here in the AZ desert than a 0w product. So with that said, does anyone have any advice on what or why this engine seems to be consuming a lot of oil. What else can it be? I just had the testing and service done last week and probably put 200+miles on the car and oil gauge is already down one notch from the top.

Car has 96K miles and I'm the 3rd owner. Could the AOS be culprit? I also have been getting BANK2 Cat efficiency codes.

What quantity of oil has it been consuming? How many miles between having to add a quart? Are you getting any smoke at startup? Just out of curiosity what brand of oil were you using before they recommended Redline? Was it Porsche A40 spec?

I am new to Porsche but long time BMW M car owner so being clear up front. I agree 1,000,000 percent with 0W oil is not the best for our desert environments which is why I run 5W-40 in my cars. I do this because the 40W is still within the manufacturer specs for the engine. Most cars come with 0W-30 or 5W-30 from factory so they can use one oil worldwide but usually 5W-40 is still within the recommended range so I run that thickest recommended range. I'm pretty sure 5W-50 is out of the recommended range now, so I would've moved to a 5W-40 instead. On top of that you are using racing oil which is great for short term high intensity operation and being brought up to temperature gradually. Racing oils often use less detergents because they are changed more often, sometimes before every race. It's just a different product. If the oil is too thick, yes it might consume a little less but it will also not flow as well. So if your car is a track car and you carefully bring it up to temp and change it often, it's probably ok but for street I think 5W40 street oil would be better overall. I'll leave the other parts about where the oil is going to those that have more Porsche specific experience but just wanted to share that. Best wishes and hope you find the culprit.

I’m was using Mobile 1 0W-40 a quart every 700 and no smoke on start up. I just checked this morning and I’m now down two bars and I’ve only driven 350 miles since it was serviced. I’m getting really concerned 😧 now

Is there any evidence of oil leaking? Spots underneath after parking it overnight? Removing the plastic shields and checking is also a good call. Do you know how old the AOS is? No smoke would seem to indicate it's OK. Before you get upset, remember that "a bar" needs to be measured against the scale on the container, then you know more precisely what is being burned. Especially at that mileage some consumption is expected, even new they consume a bit by the engine being a flat design. Lastly, (I don't recall where I read this but) I leave my oil at one bar lower than top. It's always better to run a little low than too high, that puts pressure on seals and is likely bad for the AOS too. Whatever you do in the meantime be vigilant about checking it and keep oil in her till you figure out the next move. PS What did the service entail?

Is it possible there's a leak somewhere and it's not actually ingesting oil? AOS is always a contender if you don't have record of it being changed out - if you're feeling energetic you could pull the hoses / intake tube and see how oily it is. AFIAK a slight film isn't entirely abnormal, but lots of liquid oil is a bad sign.

Thanks for responding. No leaks of any kind and the service was a oil change, test the AOS , compression test and bore scope thru the plugs not thru the oil sump.

Replacing the AOS is worth a try — but honestly it’s likely burning this much oil because it needs an engine rebuild. My ‘06 987.1S was consuming oil before I had it rebuilt back in 2017. The rebuild issue was forced because a rod bolt spun. Since the rebuild I’ve put 12,000 miles on it and it hasn’t burned any oil on the street, track or otherwise. I run the car fairly hard in HPDE. Your O2 sensors are probably throwing codes because the sensors (and likely the cats) are contaminated/damaged from all the oil passing through. I had the same contamination issue and had to replace both the cats and the O2 sensors after the rebuild to fix it. On the bright side, it still runs! A box of oil is way cheaper than an engine rebuild. I’d try the AOS first, but if that fails…just keep putting oil in it and enjoy.

If I were in this situation, I think I would just replace the AOS at this point. It’s a fairly inexpensive step. The codes you are getting about the cat efficiency could be related to putting a lot of oil related material through the cat that has deteriorated its functionality. While the AOS is being replaced, a visual inspection can be performed to see how much oil is in the breather hose and elsewhere.

Agreed, for 96k you should probably change ur AOS . You never said what ur oil consumption is. How many miles between opening another quart? I live in somewhat hot (rural) So Calif, but not like AZ (although I love driving in AZ mtns). Many yrs ago when I noticed some occasional smoke at start up, I was told to switch from Mobil 1 0W-40W to Mobil 1 5W-50W. I did and it made a difference, no more smoke. Oil consumption was probably 3-4k miles per quart during car's 10-40k mileage. But from 45k to now 65k, consumption has been constant at 1600-1800 miles per quart. I checked everything for any leaks or oil in hoses and TB, nothing. From what I've heard and read, it's the AOS slowly consuming more oil in its older age and you don't really see any smoke or leaks. The oil is probably being burnt more above 4-5k rpms and you don't see that. As a side note, best upgrade I did for desert driving is install the 3rd center radiator. $400 from Suncoast , all the mounting studs/holes are there if you have manual trans because tiptronics had the center radiator from the factory. Fun part is removing ur front bumper. Definitely get a 2nd pair of hands to help you. Before the upgrade, driving up a small mtn with AC on and 90F outside, my water temp got to 230-235F (using a Scan Gauge). After the install, same mtn route, AC now, same 90F, water temp never got above 210F. Runs normally at 188F while moving.

Shortly after purchasing my 2005 Boxster S two years ago, I discovered that it was using about a quart of oil every 700 miles. I did all the obvious checks for leaks and blow-by and even changed out the AOS but it didn't improve the oil consumption. Finally, I noticed a small leak around the bank one exhaust header gasket. I replaced the steel gasket but the leak remained. I ended up taking the car to an Independent Porsche specialist and they quickly determined that oil was leaking past the valve guides and seals. I had the shop replace the guides and seals and the car no longer uses any oil between changes. -RobT Sent from my Pixel 3 using Tapatalk

OP, just curious if the spark plugs seem "oily" The oil level so soon after filling might just be between the sensor. worth keeping an eye on.

Not only the spark plugs , but that amount of oil loss, you should see some oil droplets or oil deposits inside the tail pipes. I would look inside the two head vacuum lines attached to the AOS as well for telltail signs of significant oil. One member from Oregon had a head oil pump stop working. This backed up oil inside that head, forcing is way down the vacuum pipe into the AOS . He also was losing a lot of oil and fouling the plugs. At least your engine is clean from the injectors to bore scoring. By examining each spark plug , could you see a difference between the plugs to indicate a specific cylinder where more oil was exiting, or were they all about the same. As mentioned above, you need to fix this oling issue as its going to coat your conversters. Arizona most like uses a probe for DEQ requirements, so the cat is necessary. In the state of Washington. cars build before 2009 do not need a test. So, I no longer use the cats, Thanks to Soul , I have a set of long tube catless headers that sound and work great. Your oil usage and Red Line High Performance oil is going to lead to a big bill over time. You can unclip those vacuum head lines to the AOS to ckeck for a significant oil in each one. If one is full of oil and other is not, then check with your shop to get a repair going on that head's oil pump. These vacuum lines are to carry frothy oil or vaporized oil, not regular oil as that is what knocks out the AOS . The head oil pump sends the liquid oil back to the sump.

You said, your car was scoped from the top down, if your are thinking cylinder wear, get it scoped from the bottom up. Visit LN engineering 's web site on this an other related issues. Charles Navarro is honest and helpful. Art

I have a 981 GTS and the bar graph is just a reading of the oil quantity that has settled into the dry sump. It can be read differently from one day to the next depending on how soon after shutdown it is read. If you're really worried enough to do all that testing why don't you just drain the oil for about an hour and measure it. I always have at least 8 quarts and need to replace about that much to refill. The capacity is higher than that because the lines and coolers don't completely drain.

I replaced my AOS in 2020, about 30k miles ago, and my car is now leaking oil like a sieve. When I did the AOS I was throwing codes for cylinder misfires which since went away. I have no codes but am going through insane amounts of oil, like at least a quart or two a month of normal driving (my wife) like a normal person (going to work). And the car idles rough cold and blows exhaust smoke cold under throttle. At ~180k miles I feel like an engine rebuild is money on fire...

Did you ever figure out what the issue was? I'm experiencing very similar symptoms to yours.

@turbanator - I'd strongly suggest reading Before posting a technical question.. - READ THIS - then reposting your question as a NEW thread in the correct forum 987 Cayman/Boxster DIY, Service, Repairs 2005-2012 - giving more details on your car and the issue you're having. Welcome to Planet-9, the Friendly Porsche Forum. When you have a chance please visit the new members forum and introduce yourself and your car!