I read about DI, Carbon buildup, Misfiring, hesitation on higher RPM and seems like the issue is worst for DI Engines build by BMW/VW/Audi/MB, GM and Toyota not having that much problem not sure about volvo..
Mine 335i 97k on it start having issues around 85k with Misfiring and codes thrown, Still a CPO car took to Dealer cause was Spark plugs, they change all 6 and Car was fine. now around 92K i start seeing slight hesitation on higher gears and RPM, problem got worst every 1k I put on the car. Took it again and they finally figure out its the Famous Carbon build up on the Intake Valves, Remedy was Walnut Blasting, so Car still in garage for that procedure to be completed. Hopefully it will be 95% better.
So now come to the cause why this happening to the DI engines Design by the Brightest Auto Engineering minds in the entire Universe..
1) Cant be the Fuel since Fuel never touches the Intake Valves and adding BG44 or TEchron will not Help much may be help with Fuel injectors..
2) How about the Synthetic Oil we used, I had read that 1 person change the Oil from Mobil 1 SAE 0W-40 to Castrol Syntec European Formula SAE 0W-30. And never saw any Carbon build up on the intake valves after driving for many many miles..So is the Oil causing it and we should start using the correct oil. and what is the correct Oil to use. ???
We cant afford to keep getting Walnut Blasting every 25k from these State of the Art Engineering Machines..
My Indi shop used,
Motul Full Synthetic 0w-30, Lubro Moly 0W-30 or FUCHS 5w-30, and after 50k I been using this every 10k miles. Before that it was BMW Dealer Oil. not sure what he was using.
My Mileage from the Display which i never reset is 25.2mpg so that from almost 50k miles of driving, 60% Hwy and 40% City.
Normally people using these Oils:
--------------------------------
Castrol Syntec European Formula SAE 0W-30
Mobil 1 SAE 0W-40
Pennzoil Platinum European Formula Ultra SAE 5W-30
Valvoline SynPower SAE 5W-30
Motul FULL Synthetic
Lubro Moly 0W 30
FUCHS 5W 30
Link to Liqui Moly which is same as Lubri Moly.
http://forums.vwvortex.com/showthrea...Moly-Oil-Forum
Nice article about Moly, it did mention it helps in reducing Carbon. "Moly reducing friction which reduces heat, this helps keep rings free from carbon buildup, prevents blow-by, decreases emission, and extends oil life." " By filling in the craters and pores Moly improves this seal allowing for more efficient combustion and engine performance."
http://www.bobistheoilguy.com/moly-basics/
Another additive they been using is ceratic see below to increase Engine Life.
CERA TEC
Motor oil additive
With high-tech ceramic anti-wear protection
How does CERA TEC work?
The graphite-like structure of the ceramic particles enables them to fill in the roughness present in the metal, thereby preventing direct metal-on-metal contact. An active chemical (friction modifier) utilizes the existing friction energy to ensure flowing i.e. non-abrasive – smoothing, annealing the friction and bearing points.
CERA TEC is a suspension based on a microceramic solid lubricant and chemical active agents in mineral oil. This combination reduces friction and protects the engine and transmission against wear. This in turn prevents expensive repairs and prolongs the life of the assemblies.
CERA TEC offers high mechanical and thermal stability, ensuring outstanding lubrication even under the toughest conditions. Engine and transmission noise are reduced.
It saves energy, reduces fuel consumption and thus also pollutant emissions.
CERA TEC reacts directly with the surface of the metal and protects your engine for up to 50,000 kilometers - even with the oil being changed during that period.