I would keep using the Mobil 1. If you have been using it since you've had it, the engine should be clean.

You need to let the engine run for at least 2 minutes everytime you crank it to make sure you are getting oil pumped to the top before touching the throttle.

Replace the coolant every 18 months or so, along with brake fluid, power steering fluid, and do the transmission every 2 years or so.

Try to put atleast 20 miles on your car during your "weekly" drive. Keep the rubber seals and such wiped down with silicone.