I would use the factory recommended oil, at least while the car is under warranty. Once the warranty has expired you could use the Mobil oil and shouldn’t experience any problems.

The XV is the narrowest vehicle of its type, no other SUV we checked was as narrow, which makes your quest a difficult one. Finding a vehicle that has more grunt isn't difficult, you can check the specs of the various cars on the web, but I think you'll have trouble finding a car that fits your width needs. You might need to rethink the type of car you want.

You'd like to think that once fixed it won't happen again, particularly as it is happened to you once before, but no one can predict what might or might not happen in the future. No one can guarantee 100 percent that it won't happen again, but Subaru should be able to explain what caused the problem and give you a reasonable assurance that it wont re-occur. The dealer's responsibility is to fix your car; Subaru's should be to explain what happened and why so you can get back to driving your car with confidence. If the dealer doesn't want to help go directly to Subaru and ask to talk to an engineer. If you don't get any satisfaction go further up the company ladder until, if necessary, go all the way to the top. If the repairs are going to take some weeks as you suspect you should ask for a loan car so you're not without wheels.