usaully when that oil light comes on it means you are real real low on oil, that light wont come on till your just about dry. and i dont think theres a way to check if you damaged anything, you'd have to wait and see. i use 5w30 in my car runs fine. my friend ran his civic with very very low oil, he said the oil light would come on everynow and then and when he turned the car on the light would stay on a little longer than usual. he damaged something but we can't find what it is, but somewhere around 5000-6000 his car is losing power you can feel it lag then after like 6500rpms you can feel it pull hard again. he said it started doin it after the low oil signs. did a oil leak down and the block was still in very good sharp, they removed the head and checked everything and they still couldnt find whats wrong, but they do know it happend while he drove it without oil. its hard to tell if you messed anything up melt. i would take it in and have someone do a leak down test to see if you damaged your block or anything else. good luck.