My 2001 Dodge Stratus has 181.000 miles on it and I just had a new timing kit installed because of a tensioner problem. The mechanic at Dodge service put 5W20 oil in the car. Mfg calls for 10W30. Isn't this to thin of an oil for high milage tolerences? I do have a slight worn valve guide problem with long idiling. This thin oil makes it even more evident.
I don't know that I would panic exactly but you're right, it should have the correct oil. Your engine isn't "high mileage" in my book. My '88 Grand Caravan daily driver has 379,000 miles. It rattles just loud enough to make people in parking lots look and get out of the way of potential falling parts but that's how I know it's still running! To add to the misery, the oil drain plug hasn't been out in over 12 years! I just add a quart of 10W-40 when it rattles louder and there's no oil on the dipstick. That's about 2 quarts every 3,000 miles. You must understand that's not neglect; that's abuse, but it just keeps on going. Don't do that to your car. Keep in mind too that the thinner oil is recommended for colder temperatures. That is not for easier starting; it is so the oil will flow better right AFTER the cold engine is started. If there are no other mechanical problems with your engine, particularly the bearings and oil pump, the thinner oil should not cause a problem. If there IS an engine problem about to develop, going back to 10W-30 isn't going to stop that problem from occurring either.