relinuca

Based on four oil changes and four oil analyses, here's are the facts for my '99 996 (currently w/67K miles):

mileage Al Fe
9K 7 22
5K 3 7
4-5K 3 8
5K 2 5

The oldest event is at the top and the newest is at the bottom. All changes are annual changes and fills are Mobil 1 0W/40W.

Conclusion? The data clearly suggests that long oil change intervals should be avoided to minimize wear, and 5K is about right for daily drivers.

relinuca

relinuca

Oops...the posting kind of messed up the columns.

To explain, 9K 7 22 means 9,000 miles on oil, Aluminum ppm is 7, and Iron ppm is 22.

The ppm could be converted to mg/kg if someone wants to do the math.

relinuca

Macster

Have you torn down the engine to confirm the internals are spotless?

When I had a TDi even after 5K miles the oil was black as the ace of spades. Normal with a diesel engine. Soot.

I can't imagine how much soot TDi oil that has been in service for nearly 4 times that many miles would contain. I'd find it hard to believe the oil's detergents could keep the soot in suspension that long.

BTW, VW changed the oil change interval for my TDi (02 Golf) from 10K miles to fewer miles -- I can't recall the miles now -- because VW USA classified the area i which I lived/drove as a harsh usage area. The area? KC MO. Seems the humidity, temp changes, and dust in the air from at various times agriculture activity led VW USA to recommend (in fact specify) more frequent oil/filter services.

How did I learn of this? No phone call from VW USA or the dealer where I bought the car. Nothing in the mail. No text message. There was a notice on the VW dealer service manager's desk, a placard/sign, stating VW USA's change in the oil change interval.

Macster

That may not be conclusive or worse give on a false alarm.

There was a users ride write up in one of the UK published Porsche mags about a Cayman owner who's car smoked a bit more than normal and a borescope inspection found "scoring". Being the car was out of warranty the owner continued to drive the car and after some miles (several thousand, around 10K IIRC) the smoking was gone and the engine was running just fine.

Kazual99

So, what's the best oil to run?

Imo000

When the timing belt jumped I tore the engine apart. This was at 375 000km and it was spotless. I sold the car at 550 000km and it still had the original turbo. Diesel engine oils get pitch black in less than a day but that's just a tint and has nothing to do with the condition of the oil. I had the car for 8 years and bought it with 200 000km. What I wrote is my personal experience and not some recycled internet info.

Pac996

Best cure is grab wallet after oil change and get on the trans canada hwy once in a while for long drives to keep the contaminating gasses from polluting your oil by letting the engine blow them off during the long drives. Short around town rides heat the oil good enough to create the bad oil aspects but not blow the stuff off. It takes some lengthy riding to get the stuff to gas off.

KrazyK

Imoo
With your background you know better than to compare a diesel engine to a gasoline. Diesels run into the millions of miles without rebuild.
Diesel is a lubricant. Gasoline is a solvent. To compare the two is absurd.

Macster

One of the Porsche approved oils. If you chose to run something else, to stray off the Porsche approved oils reservation, you can make your oil selection by walking into an auto parts store and tying on a blindfold at the oil aisle and using the first bottle of oil you grab.

Your choice would be about as scientific and valid as any one's off the reservation oil recommendation.

Imo000

You are taking things out of context. My two posts are relative to each other and are related to the discussion. But to be fair, I never change the oil ahead of the manufacturer's recomended interval either.