xD suddenly acts funny at highway speed after oil change at dealership
 

I just got the oil changed on my xD at the dealership earlier this week. Yesterday, my wife told me it was acting funny at highway speed. I took it out, and the problem was clear at 70-80 mph. The car was struggling to maintain speed, dropping down to 3rd gear, running higher RPMs, and being notably less responsive to the gas pedal. I could also feel a faint pulsing.

I first thought it was a computer malfunction, or maybe the spark plugs. (It has about 64k miles.) However, I checked the oil after I got home, and it appears way overfilled. Here's a photo. If the space between the high and low markings is 1 liter, then it's easily 1.5 liters overfilled.

Could overfilling the oil cause the condition I described? Moreover, how should I approach the situation to the dealership? If their actions caused any long-term damage, I would like to seek some sort of restitution. I don't want to get ahead of myself, but the timing of the problem would be quite a coincidence if it was unrelated. Thanks.

Yes! Contact the dealership immediately. Have your car TOWED there (at their expense). I would bet that it's more like double-overfilled, probably because they forgot to drain it (either that, or they accidentally drained the transmission, leaving it empty, which could explain pretty much all your symptoms). Chances are, they ruined either your engine, or your transmission, and possibly both.

FWIW, you should never have a dealer do oil changes. They invariably put the lowest 'mouth-breather' on dumb jobs like this. I've heard this same story about 5 times over the years. Had a dealer "mechanic" once mount 3 out of 4 directional tires wrong. Plus they charge you more for lousy service. Your local "instant oil change" place does better work for less money.