Oil useage after fuel system cleaner

[myfirst63356]

Bought my 2009 Carrera S with PDK used, with 25,000 miles and 4+ years driven by the original owner.  I live in Tucson and use the car as a daily driver with once a week short freeway blasts.  I have watched the oil useage carefully and get about 1,500 miles per quart or 1,600 if I push until the low level indicator flashes.  This has been absolutely consistant since I've owned the car, regardless of the weather; and, to eliminate any other variables, I only use Mobil 1 synthetic 0W40. A month after my 40,000 mile/6 year combined service, I noticed there were no fuel system or injector cleaning items on my invoice.  After talking to the service writer, I bought a can of 44K from the dealer parts department, put it in a nearly empty tank of gas, filled it up and went on two 11/2 hour freeway trips.  I probably did a total of half a dozen hard, short blasts during the combined trips.  Subsequently I noticed that my oil useage had slowed.  Watching it carefully, I found my useage had jumped from 1,600 max to 2,150 per quart.  I'm not complaining, but this makes no sense to me especially with a direct injection engine.  Can anyone add any insights? 

[Yash]

I have seen something similar, I purchased my 2009 C4S with 8000 miles on odometer in 2012, At that time it was consuming about 1500-2000 miles/quart on the east coast (where the air can have moisture, so the actual consumption was likely higher). I moved to Las Vegas a desert climate and after several spirited drives, there is no measurable oil consumption anymore. In between I serviced the car at the dealer, who also put some cleaning agent in the fuel tank. I think either the spirited drives or the cleaning agent or both contributed to this. Its almost miraculous, since the oil bar has not gone down over the last 4800 miles!.

[JFP in PA]

The use of fuel system cleaners like Techron can remove carbon and other build up off pistons, rings, and valves, improving seal and overall performance.  That said, a lot of what the additive removes ends up in the oil, so we normally suggest using Techron in the last tank of fuel before you do an oil change.

[myfirst63356]

Interesting advice on Tehron.  I only use Top Tier gas -- Chevron or Shell.  But I stlll don't have a clue as to why a fuel additive would impact oil consumption in a direct injection engine.  It may have something to do with Yash's experience after some spirited driving.  I did more than usual in the 3 hour round trip from Tuson to Phoenix and back -- but even there I don't get the connection.

[JFP in PA]

Interesting advice on Tehron.  I only use Top Tier gas -- Chevron or Shell.  But I stlll don't have a clue as to why a fuel additive would impact oil consumption in a direct injection engine.  It may have something to do with Yash's experience after some spirited driving.  I did more than usual in the 3 hour round trip from Tuson to Phoenix and back -- but even there I don't get the connection.

 

It all has to do with the combination of the very low piston ring tension found in these engines, and deposit build up.

 

DFI injection systems utilize very high fuel pressure to obtain atomization in the combustion chamber, and any change in the spray pattern can significantly alter how the car runs.  One of the unfortunate side effects of having an injector inside the chamber is that you can get build up on the injector tip, which can alter it spray pattern and there by reduce its efficiency.  The occasional use of a high dose of a quality product like Techron helps to clean the injectors, and at the same time removes any build up in ring lands of the pistons and on the low tension rings themselves as well, promoting better sealing, and reduced oil usage.

 

A lot of old time mechanics used to tell customers to give their car's an "Italian tune up", basically take the car out and beat the Hell out of it to "clean it out".  Techron does that without the probability of getting a ticket at the same time.

[myfirst63356]

JFP -- Thank you.  That makes sense.