Another AOS thread

I just picked up a 2002 c4 cab tip with 107k miles. did a fly and drive from Denver to Austin and aside from my girlfriend backing the car into a pole, trip was almost mechanically flawless over 1100 miles. In the final 50 miles, I noticed the car would let out a good puff of smoke when taking off from a stop. The next morning, a cold start created the smokescreen typical of a spy car. I had a shop replace the AOS which seemed to resolve the issue for 10 miles at least. My house sits on top of a significant hill. When driving up the hill, the car downshifted from 3rd to 2nd. At this point, the engine let out a good puff of smoke and seemed to burn oil as if the AOS was never replaced. What are the chances AOS installed was faulty? Any other thoughts? Attaching a short video of the car idling right after the hill climb Video Link to Idle

When the AOS goes bad, it dumps a lot of oil in the intake plenum. One can often find pools of oil in the intake. Could be the shop that did the AOS replacement didn't do a good job of cleaning out the intake. Go for a longer steady drive at operating temperature and see if it begins to clear up.

I found a pretty affordable manometer and spare oil cap on amazon which you can use to test and more accurately know if yours is bad. Would recommend that

Sorry about your AOS issue. I would take it back to the shop to go over the install and test it. In reality, the factory AOS is a poorly designed part that doesnt necessarily have to fail to cause smoking. As an example, if you fill the engine oil to the full mark and park it on a hill or hit a few winding roads, there is a pretty good chance that oil got into the intake. This happens because the factory AOS cannot properly process the oil. So Porsche recomended running a 1/2 quart lower oil as a solution. But this solution isnt truly optimal because now you are running less oil and it still can't process the lessor quantity of oil properly. An easy fix is to upgrade to the UAOS w/ track drain. You wont have to worry about over filling the oil, parking on a hill, enjoying the twisties or smoking. Many other benefits to it as well.

Maybe this thread can be useful for others on their AOS journey too. I wanted to put links to parts needed to test AOS: spare oil filler cap part 99610703550 https://www.amazon.com/gp/product/B0CY6PPYDC/ref=sw_img_1?smid=ATVPDKIKX0DER&psc=1 https://www.amazon.com/gp/product/B0CY6PPYDC/ref=sw_img_1?smid=ATVPDKIKX0DER&psc=1 Manometer with included fitting https://www.amazon.com/gp/product/B07L641Q7L/ref=sw_img_1?smid=A180VU3KH6ZVF2&psc=1 https://www.amazon.com/gp/product/B07L641Q7L/ref=sw_img_1?smid=A180VU3KH6ZVF2&psc=1 Total as of today's post is $54.00

Turns out my issue was determined to be fairly innocuous. The oil change I had done before driving from Denver included 10.5 quarts of oil. That amount of oil and the steepness of my street was enough to dump oil in the intake. mechanic drained oil and put only 9 quarts back in. It�s been only 20ish miles but I�ve gone up and down the hill 4x without a smoke screen. success? Maybe

These cars only take 8.5 quarts.......and thats if ALL the oil from the change has been drained. I usually only go with 8

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What should it read during the process? Number wise I mean.

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That's not exactly accurate, on the 996.1 cars and the early 2002 996.2 cars up til engine # M96/03 662 11805 VIN # 99 Z2S 60 3565 the OEM Factory fil was 9.25 US Quarts ......on the later 2002 996.2 cars after engine # M96/03 662 11805 VIN # 99 Z2S 60 3565 the OEM Factory fill was 8.75 US Quarts........The total engine oil capacity is 10.66 US Quarts ( dry engine after rebuild ) All 996 and 997.1 Carrera's have the same engine architect but the reason for the lowering of the oil level by .5 US Quarts was the inadequacy of the OEM AOS System,.... Porsche lowered the oil level instead of increasing the efficiency of the AOS System ( UAOS )......a cheap fix but not good for Track Work or aggressive Twisties Drivers..

Interesting because my cars dipstick registers full with 8 quarts and I do let it drain to the point of dripping, plus the gauge on the dash registers full as well. Not saying you're incorrect but wonder why my .1 would only take that amount (8) if it should be closer to 9+?

I've only started my journey to learn the nuances of the 996, but when it comes to dipstick measurements I understand there are 2 different dipsticks that were available in the 996. The older style ( 996‑107‑14‑55) recommends filling the oil level to a measured halfway point. the newer style ( 996‑107‑14‑55) says you can fill to full and will avoid over-filling. This is simply a measurement and reading consideration. The AMOUNT of oil seems to be specific to the engine per @ Porschetech3 comment I'm sure if I. misspoke - someone will correct!

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Yes, you were 1qt over filled. Way to much for oem AOS to handle. OEM AOS even have a hard time with the correct oil level... Its amazing how efficient PT3's UAOS is to be able to handle 2 extra qts of oil without a problem, not allowing any oil into the intake. Actually mostly solving the m96 catastrophic problem of oil pressure instability, at least on the street. With all that oil in the engine its very hard to run the sump dry and starve the bearings. Almost impossible on the street and takes a real track rat pushing to the max with <200tw tires to get OPI on track with 2 qts extra fill & UAOS... I take off my sump plate every oil change and have a look around. (its easy and gives a great harbinger to whats going on in engine currently) . It drips over night or sometimes leave it on the lift dripping for days... It takes 9.5 qts on both my 2001 996.1 & my 996.2 2002 to get to full on dipstick, both have original dipsticks. This is on a level garage floor first thing in the morning after sitting all nite. Not on gauge cluster. Bottom line, just as PT3 explained, Porsche compromised with a 'superseded/updated 1/2qt lower oil level dipstick' on later 996.2 to avoid aos being overwhelmed. All at the cost of engine bearings getting run dry in spirited driving. So with the choice of blowing smoke and possible hydrolock from easily overwhelmed oem AOS, lower oil level was Porsche's 'fix/compromise'. At the cost of starving bearings of oil in spirited driving. We see this all the time here with many stories of m96 spun bearings, rod knock, etc, maybe a few times a month here... A sports car that can't do continuous spirited high G driving is absurd, let alone a Porsche with its racing heritage. Just as a Porsche that hydrolocks its engine from an under engineered defective easily overwhelmed oem AOS. Beancounters

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VVVV Correct ...