OK, some additional info... reviewed the vehicle's service records with the service manager today. Dealer last saw vehicle 3 weeks ago, while under warranty; was brought in for complaints of decreased fuel economy (approx. 20% reduction) and driveability issue. Insisted that real time data be captured and saved, not just SDS Quick Test. Was told at that time that no faults were found.

But today, upon reviewing the service records, turns out that fuel adaptation was maxed out... but since CE light was not on, technician had merely reset adaptation. And reported to service advisor that nothing was wrong. And this is all documented.

So, after revealing this, the service manager requested the vehicle be driven for a couple of weeks more and then brought back in for a recheck. If faults are found, they'll "work with MBUSA on arranging some sort of fix out of warranty." Guess that means they'll pay for only the parts.


As for the oil... that's an another dealer fiasco. Vehicle exhibited some noisy lifters last fall, so changed from Mobil 1 0W-40 to Mobil 1 15W-50 and then drove the vehicle for approx 2K miles. Lifter noise remained and when vehicle was taken in for warranty service, dealer was advised of continued lifter noise, despite the use of the heavier weight oil. Later that day, the service writer called back stating that because 15W-50 had been used, the top end of both cylinder heads was likely irrepairably damaged and that new camshafts, lifters, etc. would be required. For approx. $5k. All this because the wrong oil had been used. No complaint regarding engine performance, no tear down, just a blanket statement that use of the wrong oil had caused major damaged and a request for permission to overhaul the top end. On a engine with 35K miles.

Immediately contacted Mobil and advised them of the dealer's claim. A couple of minutes later, after they finished laughing, Mobil stated that there was no way their synthetic oil could cause that kind of damage in 2K miles and if it did, they would cover the damage. They requested an oil sample be taken from the engine and sent to them for analysis.

So samples were drawn and sent to Mobil, as well as an independent lab. The dealer renewed the engine oil, using Mobil 1 0W-40. And quietly backed off their claim of engine damage. The oil analysis reports from the two labs revealed absolutely no signs of any faults, including elevated levels of suspended metals from accelerated engine wear.

The current oil analysis was performed just to substantiate the findings of the first oil sampling, which it did. It was completely fortuitous that the fuel-contaminated oil was noted, since it was not expected nor being looked for.