Quick Question - Is there a service interval on the 987.2 AOS

I cant seem to find one. Any one know or have suggestions ? I have no smoke at start up , no oil burning that I can tell , idle seems normal but mine is now nearing 12 years old

I replaced my AOS at 10.5 years, 244000 km. 2008 base Cayman .

I'm putting in a new one in due to age not mileage. I had one go on my 986 , there didn't seem to be any issues with replacement after failure but you aren't driving the car till it's replaced and nobody is going to tailgate you to the repair center. For a $115 it's cheap insurance. I will complete a spring service interval I believe would total at least a couple grand at the dealer for about three hundred bucks.

I think I will plan to do mine in the spring as a PM, not many miles will be driven over the next 2 months or so , thanks!

I did mine at the time I did spark plugs and coils even though I had no symptoms of a bad AOS . The thinking was that I didn’t want to risk fouling new plugs. In my opinion the AOS is an item best replaced as preventive maintenance.

sounds like a good plan. I looked at a few videos, seems pretty strait forward

I think you guys who are interested in replacing your 987.2 3.4 L AOS should be thinking about the carbon build up on your intake valve stems. HYAK did a walnut service to remove the carbon buildup and a catch can to help remove the smoky blow by oil. I would recommend using the lowest NOACK value, like using Redline High Performance oil, which has the lowest oil evaporation of any oils tested. Here is Redline High Performance motor oil description. "Produced in only one top-of-the-line grade, these products offer the highest quality available on the market today and in the widest variety of viscosity Full-synthetic ester formula for passenger cars, light trucks, performance vehicles and marine applications Designed to provide the highest protection, efficiency, cleanliness and superior drain intervals Excellent wear protection and friction reduction across a wide range of operating conditions High detergency allows extended drain intervals and provides increased cleanliness Improved fuel economy and ring seal for more power Superior high temperature stability and oxidation resistance increases lubrication of hot metal compared to other synthetics High natural viscosity index (VI) provides thicker oil film in bearings and cams Less evaporation than other synthetics for improved efficiency and ring seal Blended with polyol ester base stocks that feature natural multi-grade properties, avoiding unnecessary additives that hinder lubricity All products are completely compatible with other conventional and synthetic motor oils" Bullet point #8 was confirmed by a test done by a competitor, AMS oil confirming their standing among other top grade oils. I'm not sure why this topic has not gained more attention. LN makes a product DI40 specifically for this reason. I am not using this oil as I have a port injected M97 engine so no worries about carbon built up on the intake valvue but use Motul 300 v Power for other reasons. I am using Redline High Performance for my wife's Audi Avant, which is a DFI 2.0 turbo engine and prone to intake valve carbon build up.

Bunch'a good stuff snipped.. I think this would be more accurate if it said: I think you guys who are interested in replacing your 3.4L 987.2 AOS should be thinking about the carbon build up on your intake valve stems. The reason I say this - the 2.9L engine doesn't suffer from oil-crud on the intake valves - it uses port injection which sprays on the back of the valves, and if you use decent gasoline has cleaners in it to remove that sort of deposit. I'd be interested in knowing if the catch-can actually does much or captures much oil. Any ideas on that? Most modern direct-injection designs now add another injector designed to provide gas-vapor streaming in the intake tract for exactly that reason. Direct injection is a great thing for power and efficiency, but it does have that one flaw of not providing any cleaning medium to the back on the intake valves.

wow , you guys know your stuff!

Apex1, What weight oil are you using on the Audi ? It's interesting that the Redline 0-40 High Performance has a NOACK of 9 while the 5-40 is 6. That's a pretty big difference. Are you using the 5-40 in the Audi ? The Redline High Performance line does not seem to have Porsche A40 or C40 approval. It just says it's suitable or suggested for. Interestingly enough their less expensive Professional Series does have the Porsche A40 approval. But the NOACK value for that is higher at 11. Hmmmm. Just as a comparison, the Liqui Moly 5-40 Leichtlauf which I have in the car now has a NOACK of 10.

I use Redline High Performance 5W-40 in the Audi 2.0 l TDI motor. This is after my plugs looked caked with carbon. I do not live is low temp environment, rather in Puget Sound area near Seattle. Thanks for looking up thiis data as its more important to us on Porsche DFI engines rather than the Audi . Take a look at Hyak thread on his walnut blast to clear the carbon from his intake valves. He also added a catch can. to trap smokey oil from the sump, so he is getting blowby from his rings pushing that evaporated sump oil through his AOS and into his intake manifold. There is no gas in a DI manifold to rinse the intake valves of this oil mist. I tried to get him to use Redline, but its up to him and his catch can. Most owners of the 9A1 engines have no idea about intake valve carbon build up. Thank goodness for that Redline High Performance product. At least there is a product on the market to fill that product need. Joe Gibbs DI40 also is trying to fill that need, but I have yet to see an actual independent oil study outside of LN. The NOACK study was actually done by AMS oil showing 6 with Redline High Performance 5W-40. 10 vs 6, I'm actually not a fan of Redline High Performance products, but for this issue, I see the need and see how this product can fill that need. I use Motul 300V Power in my port injected 3.4 l M-97 engine. So, I am used to paying for these types of oil products.

Based on what I'm gathering on this topic, it seems the best way to deal with carbon buildup on a DFI is: 1) Use an oil like Redline or Driven DI40 designed to reduce evaporation of oil and carbon buildup. 2) Use an oil viscosity that is not lower than it needs to be based upon temperature at which the vehicle is operated. (I might use 5-50 over summer for the track). 3) Keep oil level in the mid to lower/mid of the gauge range rather than topped off. But monitor regularly so consumption doesn't take it too low. 4) Keep the oil change interval fairly short. 5) Replace the AOS preventively and clean out any oil in breather hose and other areas periodically. These seem like the best measures to take short of making hardware changes like a catch can or changing the sump.

Just an open question... is there actual proof that a lower NOACK oil will reduce or eliminate carbon on the valves? I totally agree that this is a great theory and idea, but I'd love to see conclusive data if it exists. A quick search on the topic has mixed info about NOACK correlation to deposits... but many seem to say low SAPS is the more important thing to watch for. I admit, I haven't done a full dive in the matter, but this is what I'm seeing initially at least. One reference: Low NOACK, SAPS and TEOST oil for DI engine

Oil vapor vs oil droplets. Can a catch can catch both or just the droplets. That's the reason I was trying to get HYRAK to use one oil for a couple of races, measuring the catch can amount and the amount of oil loss in the sump. I believe he was using Mobil 1 5W 50. Then switch oils to the Redline High Performance 5W40 for the same track and temps and measure the collected amount in the catch can (oil droplets) as well as how much oil is used/burned as vaporize oil out of the sump. The measure of oil in and oil out to find out which oil causes either droplets (catch can) or evaporation (oil vapor). I believe he is interested, but not to a point of actually doing it for our benefit. His concern was the amount of oil his engine was actually using over a week end event. If he narrowed his oil use to either one, he could reduce his usage. If he determines its from oil droplets, then Redline would be the product, however if its from oil vapor, then some base oil that is non synthetic. I did not see a listing of those oils. The big question is does this actually relate to how much carbon collects on the intake valve stems. So, HYRAK would have to do a test long enough to actually see the carbon build up with one oil (vapor synthetic )and not with another (base oil non synthetic). This may take years. Eventhough he actually cleaned his intake valves with walnut blasting, I'm not sure he wants this point as his end game. He just wants to reduce oil consumption. He is the only person that actually looked at his valves and cleaned them. Then started asking about how to reduce oil consumption. LN on the other hand with D!40 I believe is thinking oil vapor is the issue, not oil droplets.

Lots of variables. One thing I remember about Hyrax’s story is that he had no oil consumption issues in street driving. Only on the track. And it’s not clear how different his intake valves might have been if the car had only been street driven. The track presents an environment of higher engine temps which could lead to greater vapor. The track also has high g forces so droplets could be escaping. Or both of these variables can come into play. We are also assuming that his oil consumption is related to crankcase oil/vapors escaping through the AOS . While that is certainly something that happens with our cars, there could be oil getting past the rings as well. I’ve seen things indicating that modern cars have less tension on the rings to decrease friction and provide better mileage and emissions. Its one possible reason that many manufacturers are saying that consumption of up to a quart of oil every 1200 miles is “normal”. I’m not sure if this is the case with our cars. But many newer cars have serious oil consumption issues.

JamesBond, before and when you do your AOS , check the condition of the entire vent tube that connects to the AOS . Mine had tiny cracks in many places, plus it cracked majorly during the AOS install. The tube is typically a special order part and costs around $100. Getting the AOS out and into the engine compartment was the hardest part of the install for me. Had to invert it and rotate it - there is a vid on youtube where the guy shows the technique. My rationale for doing the AOS was the same as Greg's above - I'm about to do plugs and coils and don't want a bad AOS system fouling them.

The key here is to find a happy medium between oil vapor and oil droplets, two different properties of engine oil. The insert I copied below suggests that the more modern synthetic VW502.00 caused less vapor but more deposits than the Low SAPS VW504.00507 Unfortunately, I do not have a copy of the Lubrizol study. So, I guess until I find a copy, I'm sticking with Redline High Performance 5W40 for my Audi A4 TDI due to its low NOACK score of 6, (meaning an extremely low volatility/evaporation rate). The AOS issue is also up in the air. Do we know if the Porsche AOS 's pick up the small oil droplets and deposit them back into the sump or allow them to pass through the filter like the oil vapor. What size is considered a droplet and what size is vapor? If someone could confirm that these droplets are prevented from entering the intake manifold by the AOS filter. Lubrizol study is available here somewhere on European forum. High SAPS VW502.00 left 167% move deposits than Low-SAPS VW504.00/507.00 oil did. So, it is not consensus, there is actually scientific proof. What vehicle? So, use as low NOACK score oil as possible and have an AOS in good working condition that traps the oil droplets.

If you track often, one option is a Porsche Motorsports AOS , but they are pricey. The Motorsports AOS for my 987.1 BS, part 987-107-926-00, seems to run about $1,500.

I currently have a Porsche Motorsports 987.1 AOS , It was installed due to the windage plate on the top of the LN deep sump. The windage plate came with the deep sump expander aluminum ring that was installed to extend the sump for more oil capacity. The downside of the windage plate is that the return oil hits the plate and the G forces slides that oil up the sump walls before it can drain into the sump. The AOS sits on top this suction/vacuum hole on the top of the sump. After breaking 2 OEM air/oil diaphragms in the AOS 's, I changed to the 987.1 Motorsports product. I also run 3/8 level oil in the sump. Between these two facts, I have not had any problems that I know of. The reason I bring this up is that I do not know if the Motorsports AOS has the ability to filter smaller particles of oil than the regular AOS . All I know is that it is more robust and can withstand more oil downs from my sump system. I explained my AOS situation with LN, and they said, the 987.1 Motorsports version will withstand all the G force loading that my Hoosier A7 can achieve with their windage plate in place. The reason is they managed and ran 10 customer cars with this system without an Porsche 987 .1Mortorsports AOS failure. They also demanded that the sump oil fill not exceed 3/8 level. I am still running close to 10 qts of oil though. So back to this discussion, I do think the 987.1 Motorsports AOS does filter smaller particles of oil than the OEM version. I am not sure how this AOS compared to the 987.2 9A1 motor version AOS though, especially the oil filtration of small oil particles.

I recently had my AOS replaced after one season of track driving on my '09 Cayman S . I was told by my mechanic that the Motorsport AOS does not fit the 987.2 . Further, the MA121C (9A1) engines don't need the expensive AOS system. I can't give you all the technical reasons for that but I trust him. The 987.1 is a different story. To the question of how often to replace the AOS - there is a way to measure the the system without taking the covers off. Again I don't know the technical details. But I am sure any shop that works on Porsches will know what equipment to use and how to perform the quick test. Question for Apex1 - I assume you track a 987.1 ? So the Motorsport AOS fits. If you have a .2 my statement above about fitment could be argued. Also - have been running Motul 8100 Ex-ess 5W-40. I want to switch to the Liqui Moly primarily to buy from FCP Euro for their lifetime replacement guarantee policy. Do you use the 0W-40 or 5w-40? Has LM been holding up for you? Since we just completed a major suspension upgrade I will be running Hoosier R7's this year. Your comment about lower oil fill level is of interest to me also.

So from the bottom back up your post. I assume you up graded your LCA's and put in stiffer springs, coilovers and changed to adjustable swaybars and down links? These are necessary to run Hoosier R7's according to their package insert. They specifically call out camber of over -3.0. They talk about air pressure and other stuff. So the idea is to get more g forces in cornering which leads to oil containment in the sump. I would suggest looking at a deep sump with internal gates to prevent the oil from sloshing around. I also believe your mechanic that the 9A1 engine AOS is more robust. Not sure its the same diaphragm material as the 987.1 Porsche Motorsports version but better than the 987.1 OEM one for sure. What this does for oil droplets is another story as HYRAX found out. I am using Motul 300V Porwer 5W 40 for the past 2 years. This product was used by a couple of members who graduated from the 987.1S to GT4 's without any engine problems and 200 track days. They were running LN deep sumps and the Porsche Motorsport AOS . So I figured if they can run this oil, I will change as well. I don't like forking out $100 per oil change plus the LN screw on oil filter with magnets. But, I have had absolutely no issues with my motor or oil usage. This particular oil has no ZDDP which eats plastic parts. Some of which are the plastic coating on the 987.1 piston skirts which effects the cylinder walls causing bore scoring. Another feature of this particular oil is high temp use and low oil psi in certain corners with racing slicks. This oil protects the #6 rod bearing form scaring in oil starvation situations. The reason I use 3/8 fill is instructions directly from LN to keep the oil from climbing the sump walls and entering the vacuum hole in the top of the sump connected to the AOS . I would suggest going back to HYRAK thread and read about his oil issues with the 9A1 engine. The AOS test you are referring to is a vacuum test on your oil filler. There is a vacuum meter that attaches and can easily be read. I would look to see if the GT4 version AOS will fit the 9A1 engine. If so, that's what I would be using as I don't believe I have read anyone using a 9A1 Motorsports version. I would call LN to get this info directly from Charles Navarro, who puts out monthly bulletins on racing issues with both M97 and 9A1 engines. Of coerce Charles would recommend his DI 40 be used for racing and his screw on filter system. LN also has a oil analytic department to help give accurate analysis of Porsche specific problems. The oil droplets issue and using a catch can like HYRAK does maybe rectified with the GT4 AOS . Again, see post #10 regarding the use of Liquid Moly and their life time replacement guarantee policy.

You can measure crankcase vacuum at the oil fill cap. On the 987.1, if the vacuum is too high there then the AOS has failed. The 987.2 AOS has higher crankcase vacuum by design than the 987.1 version. So not sure if it can be tested the same way, but if so don't use the 987.1 spec.

Your car will let you know if the vacuum diaphragm in the AOS as failed. I have not heard of 9A1 AOS wholesale failures like happen with the M97 engine . So, Porsche may have up graded the AOS system in the 9A1 to be more robust from oil wash down from the sump in high G corners. But again what about the oil droplets that could be passing through the membrane without our knowledge. The oil vapor certainly does.

Apex 1 - you are correct about my suspension upgrade. It did include LCA (RSS GT3 Cup), MCS shocks, Eibach springs , GT3 sway bars and all of the other assorted accoutrements both front and rear. The only thing I didn't do was upgrade to larger Brembo brakes or add the GT3 Brake booster and master cylinder . I'm sticking with Sabro rotors and Padig RS29 pads for now. Now have -3.5 camber in the front. Also going to 18" wheels from 19. I was going to go with the LN deeper oil pan but my mechanic recommended no. So we stayed with the standard pan. According to him, the 987.2 oil system is robust enough to prevent starvation on aggressive corning. It acts like a dry sump and should provide better distribution of the oil without have to lower the bottom of the pan. I not a hater of going deep but I like not having anything below the bottom panels. With the new suspension and wheels, I'm about 3/4" lower already. Gubi - I believe the vacuum test was used to test my 987.2 last summer. We replaced the standard AOS in June 2021 and again in Nov. 2021. That test should work on both models.

Apex 1 - you are correct about my suspension upgrade. It did include LCA (RSS GT3 Cup), MCS shocks, Eibach springs , GT3 sway bars and all of the other assorted accoutrements both front and rear. The only thing I didn't do was upgrade to larger Brembo brakes or add the GT3 Brake booster and master cylinder . I'm sticking with Sabro rotors and Padig RS29 pads for now. Gubi - I believe the vacuum test was used to test my 987.2 last summer. We replaced the standard AOS in June 2021 and again in Nov. 2021. That test should work on both models.

It works, but the spec is different. The 987.2 will show higher vacuum, so if you use the 987.1 spec the AOS will look bad when it may not be. Some mechanics do not realize this.

It seems to be a time issue, not mileage. My 2009 has 18.000 miles on it and I noticed that I was getting very poor gas miliage. About 14 around town. Then I started getting a puff of smoke about every 10th cold start. I checked it with a manometer and it read high in the acceptable range. Went ahead and replaced it and that solved both issues.

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