Case Studies

Porsche 911 – Smoking On Start Up – Q & A And The Why

Background – Recently, we had a client ask us about slight oil smoke at the start up of his Porsche 911. If one person asks, it usually means that at least ten other folks have the same question. So, we thought sharing this here might be a solid idea.

Question – “Hi Bruce. Thank you for the follow-up note. Much appreciate your work on my Porsche 911. Question – when I start it up cold, It does blow some smoke. How concerned should I be? Or not. It’s got 45k mileage and is now ten years old.

Answer – Very common with 911 to have some slight smoke on start up. It’s the nature of the Porsche flat 6 engine that oil can seep into or past the rings when the engine has been sitting some time. It should clear up in a few minutes of running.

Technical Reason
The technical answer is that the smoke on start-up is caused by the engine “wet sumping”. That is, some the oil in the oil tank drains down into the crankcase overnight. The 911 engines are a dry sump oiling system. This means, that the crankcase is purged of oil when the engine is running.

Also if your oil tank level is slightly too high the sump can fill and oil can enter the cylinder, via the rings and cause the smoking at startup. Even a different parking angle can cause this condition. Once the engine is stopped and over time, the oil works down into the crankcase and floods the bottom end. That oil level is now backed up against the pistons and crankshaft.

Once re-started some oil has saturated the piston ring packs and the crank webs, and you get smoke till it burns off. It is not a problem once running as the oil pump has a pressure side and a scavenge side. The scavenge side has much more pumping capacity than the pressure side and quickly empties the crankcase of oil. The trick to keeping a 911 from smoking at start-up is to drive the car every day and be sure there are no air leaks in the breather (that long hose from the back of the engine to the top of the oil tank).

A link to an excellent article with more detail can be found at –

Avoiding This
Factors that make it less likely include a good service history and a usage that isn’t inner city or predominantly short journeys (where the engine is always running with a rich mixture and excess fuel can dilute the oil). The 20K/2yr service intervals also haven’t helped with engine life when diluted oil isn’t often changed in such an urban environment.

Preventative Maintenance
We would strongly advise changing your car’s engine oil every six months or 5,000 miles, preferably with oils formulated with increased levels of Moly additives that most oils do not have, which in turn helps to protect the cylinder walls. Doing so will help the oil remain free of contaminants that could lead to Porsche cylinder bore scoring. Models that have been well maintained with good service history and a healthy cooling system will reduce the chance of localized overheating. More frequent oil changes may be necessary if you track your car, drive short distances, or operate the engine in cold climates.

How We Can Help You
The Service Team here at Atlantic Motorcar is well experienced in this issue and others; with over 35 years of European auto specialization, serving clients from the areas of New England, we are familiar with the needs of the special service of your auto.

As Maine’s leading European auto specialists, we provide expert-quality services at a fair rate than nearby dealerships and specialty shops. If you’re experiencing any of the above-mentioned symptoms in your auto, please call us immediately; we can usually see your car the same day! At Atlantic Motorcar, we’ve developed some very specific procedures and tooling, combined with our expert technicians, to make this otherwise onerous repair a snap.

Questions or if we can help with service on your Audi, BMW, Mercedes, Sprinter, Honda, Infiniti, Lexus, Mini Cooper, Porsche, Volvo, and VW, please contact us. Our team of Service Specialists is here to help, for even the newest autos! (207) 882-9969.

Knowing, not just “doing,” that’s the Atlantic Motorcar Center way.

The Atlantic Motorcar Center Service Team

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