Good morning guys,

After 120k miles of great service. My 955 got a bore scoring.

It burns oil and gives a few seconds of smoke on a cold start (after a long trip, it doesn't smoke on a cold start after short trips). I checked the compression and cylinder #5 pressure was 130 psi. There are carbon deposits on the spark plug.

Put a camera down the cylinder and confirm my worst fear.

https://imgur.com/a/j2mAIUF

I have 5-50 oil on hand so I'll start using that and will start looking for a new car shortly. The body is still perfect (garage kept), and the leather seat is still perfect. It still runs well and pulls hard.

Saying that I am disappointed with Porsche is an understatement. I also have a 20k-miles 911S (no issue) and that may very well be my last Porsche.

 

Really sorry to hear that. And here I was just the other day saying that we hadn't seen a case of 955 scoring on here for a long time. Hope I didn't jinx you.

Where do you live? Cold climate region?

 

Ugh, that sucks.

What were you using for an oil change interval (miles and time) and what oil?

Where does the car live now and what other areas has it lived in throughout it's life?

 

I got the car since it was new. I was using mobile 1 (5-20w) every 5-7k miles or so. Serviced at the dealer until the warranty ran out and I did it myself.

It's been in the Philly area all its life.

I put in 5-50w oil and took it out today. No smoke at all. However, it didn't always smoke, so I'll keep an eye out in the next few days.

I'll change the oil every 3k miles and the spark plug on that cylinder every 1k miles. I removed the coil cover and the bottom shield to make the oil/spark plug change easier. If I do that, I think it'll last another 30k miles (for a 150k total). It's an experiment at this point.

EDIT: I was using 5w-30 (not 5w-20) on the Cayenne S. That's a typo. It's my Lexus that uses 5w-20.

 

That wasn't the best choice of oil. 5w20 is too thin a hot viscosity without enough film strength to protect the cylinder walls and Mobil 1 breaks down from a viscosity standpoint in as little as 3k miles from the UOA I've done on it with my cars before I switched, so running it to 7k miles, also not great.

Hopefully, you're not using this same oil in other vehicles. Do you have any used oil analysis reports throughout the Cayennes life - I'd like to see the metal wear, viscosity indices, and remaining zinc and phosphorous content in the used samples.

 

I'll have to agree with Petza, sorry. Mobil 1 gets the advertisement because Mobil pays big money to manufacturers but it isn't the best oil and 5w-20 is on the thin side. I'd use at least 5w-40 and a better quality of oil. Your oil change intervalse are fine with a better quality of oil but Mobil 1 will get you through the warranty and then some but not for "Lifetime". Most manufacturers tend to list about 1 grade thnner oil than what is best for their motors. The thinner oil gets them through warranty and then some but isn't generally good for long term. It is a fleet wide EPA fuel economy efficiency thing. A 0.5% fuel economy increase doesn't sound like much but when the EPA has a fuel economy standard and over all of the cars the manufacturer sells it makes a critical difference.

 

I do enjoy Toyotas 0w-16 nonsense with the same engine calling for 5w-30 on another continent

 

That's my typo, it's 5w-30 (not 5w-20).

 

That's my typo, it's 5w-30 (not 5w-20).

 

Getting better, but 5w40 and something other than Mobil 1 would've been better
​​​​​​.

 

Probably $10k for engine rebuild. Is there anything else you could buy for $10k that would even be half as good?

 

https://www.cars.com/vehicledetail/67b7fafa-1cc8-4de7-b6a2-a0ae9bfa5f1e/?attribution_type=se_rnp