Took the 2000 Volvo v70 xc wagon out of storage to drive around town in.
Things started off fine for most of the day, nearly put 300 miles on the car doing errands.

Then in the evening running to go see my youngest play soccer on the way down to him the oil light goes on the dash. I get into town and check the oil level. Seems okay, but I figured I better have some oil on hand. Recheck and top off. Start the car up the oil light goes out as I'm traveling 5 miles down the road up a hill the oil light comes on again. I get to the nearest place to stop and check the level, the level seems fine. I start the car again the oil light is out. I get near the place for my sons soccer game and the light goes on.
Okay at this point I figure I wouldn't be back in the car for an hour or so. So, I figure to let everything cool down. Hour and half later I check the engine compartment and can't find any oil leaks. I check the oil level and it was maybe a quarter quart low. So I top off. This time though I start the car and the light stays on. I crawl home with the car like this and try to avoid any hills that I can so I put no pressure on the engine. I get home and the car limps up the last hill at about 15 miles an hour, park the car and let it sit for a day or two. Then I go out on a weekend morning and check the oil level. It states that I'm about 2 quarts more than I should be now.

Any ideas as to what is causing the oil light issue, poor oil level reading, and the lack of power? Please advise. Thanks.