Mdrums,

What's your current mileage?

 

I just hit the 10k mi mark, and have probably put at least 5 quarts into the car. Every porsche mech that I speak with has told me that this is quite normal. There have been no signs of leaking/seepage, so I bet it is quite normal....

 

Wow, my 07 C2S is at 17k and has only used 1.5 quarts. What's the cause of the greater consumption for the DFI cars?

 

6400ish

 

FYI - 2000 break in miles, zero oil consumption. Oil and filter changed. 600 miles including a DE event, no consumption so far.

 

You are 1 lucky guy!

 

Oil is not the thinnest when it it cool.

Porsche just has no quality control and makes many crap engines. It's not anymore complex than that. Top it off with filling these loose engines with Mobil 0W40 and they invite oil burning.

 

Any improvement at all as the mileage accumulates?

 

1400 miles in 1.5 month and I just added 0.5 quart couple days ago. Majority of the milage is from highway. Tail pipes have black soot but no worst then my 2006 E55.

John

 

Which Mobil 1 are you adding for a 997.2...........alot of track use

 

Yes it has goten a little better. I have a 2 day track event this weekend so I will report back and see how the oil burning does.

 

What did the dealer say about the soot on the exhaust tips.

 

09 C2S with PDK.....1600 miles ...have added 2 quarts of Mobil 1 0W40....black soot present on tail pipes

 

These are characteristics of a DI engine.

Here is a German technical paper on general oil consumption during break-in. This engine was at full load for the entire test and still didn't stabilize until about 400 hours of use.


Different engine all together, but you can kind of get the idea.

DI engines do not come without fault. Perhaps some of you have read my write up already on these. These engines will have performance issues after some moderate use.

Here is the over simplified short version... the intake vales no longer are washed with fuel. They are super heated and dry. As most of the left over fuel and blowby oil is recycled from the cylinder chamber back through the intake, that residual oil and those particulates of fuel that were not burnt now are in direct contact with those hot/dry intake valve. Some of that bakes itself to the intake valves. Over time(from a few thousand miles to maybe 15,000[I am guessing since this DI engine is too new still]) the timing is pulled back to deal with the lack of smooth air flow via the intake valves.

Because it comes on so gradual over the 1000's of miles you won't feel this. But your car is getting slower and less fuel efficient.

That actually is the short version. The long version explains how I studied the recycling system that Porsche made and how internally the concept it's very similar to Audi's. And you may already have heard that the FSI(Audi's DI design) is plagued with this issue severely, especially the RS4 and R8. But I won't get into all of that.

This isn't to say that all the oil you are burning up is going on your intake valves. That's silly. That was just a side note. The oil burning goes back to the beginning of my post, normal burn in for a new engine(within reason). Some of your oil burning is NOT normal but will most likely taper off in the coming months. But this "missing" oil in your engine is on your tail pipe or getting layered up in your Cat. If you heated your tail-pipes up to 1000 degees for a while you'd see what your intake valves are looking like, baked on carbon and residual gasoline particulates that will only come off with an atomic bomb blast(or hours of cleaning).

One more thing. Once your oil consumption tapers off, I COMMAND you(ha) to send a sample of your oil to BlackStone or similar oil analytical labs for a review. Plenty of DI engines are also seeing critically high fuel dilution in the oil. And when your oil stops going down on the readout, it could mean it's still burning but being replaced with raw fuel instead. High fuel dilution in oil means the flash point of the oil decreases at a frightening degree. I'm seeing fuel dilution at 5-6% in some! That is 5-6% of your oil pan is gasoline mixed in the oil. That is serious trouble. 1-2% is "normal". High fuel dilution is an engine destroyer.

EDIT: I have absolutely no affiliation with BlackStone. I am just an Engineer outside the world of automotive.

 

Interesting and time will tell. To counter this Diesel's have always been direct injection and never had cooling of valves from fuel. I have been in numerous diesel engines, I used to farm, and never had build up on the valves.

Peter