Re: Will the wrong oil weight cause damage?
Assuming it is Mobil1 5W-30 synthetic, then it is highly unlikely it will cause problems. However, the mfr recommended 0W-40 for a reason and that's what you should use. When I bought my SRT6, the dealer had used dinosaur 10W-30 and it had been test driven multiple times. I had him replace with the proper synthetic before taking ownership.
If cost was an issue, I would use Mobil1 5W-30 or 5W-40 in hot weather if it was cheaper than 0W-40 and my warranty expired. I would definitely use 0W-40 in a cold winter climate. That being said, I also decided that the $5-10 difference to buy 0W-40 was probably good insurance since I only change the oil annually and want the car to last.