The oil was changed by a highly reputable shop 2 days ago, (45 miles ago). My wife noticed today that the "Low Oil Pressure" red message flashed 3 times in the last 5 miles of her 10 mile trip (45-50 mph). She stopped the car and called me. I arrived at the parked Prius and saw no oil on the dipstick. I poured a quart of synthetic in and looked under the car to see it pouring out. My finger discovered that there was No Oil Plug. I called the shop and they sent a tow truck, put a new oil plug in, refilled the oil and claim no damage since "the Prius shuts off the gas engine when low oil pressure is sensed". Can anyone lead me to information about this "shut off feature?" What should I ask from the shop? What should be tested & checked for? How do you test for damage to the bearings? How about a compression test? The car has 100K miles. Thanks !