Beware, I own an SR20 and recently had an oil change. After landing from my return from the oil change I noticed A LOT of oil dripping down the entire underside of my fuselage (several quarts worth). I opened the cowling cover and discovered the oil cap was OFF! Upon landing or Taxi the cap came off because 1) it was not tightened by the mechanic, OR, the gasket and flanges were insufficient to create a tight, secure fit and it vibrated loose and off. Interestingly, none of the oil discharged out of the oil filler tube, rather it was discharged out of the breather tube. I lost 3 quarts and thanked my lucky stars it happened on the ground, AFTER my flight. Has anyone ever experienced an oil cap vibrating off on it’s own??? I crimped down the flanges on the inside of the cap to create a tighter closure. Be sure to check your tension as a cap left off will discharge most (or all) of your oil in a hurry!. This sure seems dangerous! Any other expert opinions welcomed.