I got my oil changed some months ago at a repair garage, but recently by looking at the recipe they gave me, I noticed that they commited the mistake of putting the wrong oil, my car is a 1991 corvette, and the mechanics put 15w-50 instead of 10w-30 (which is the right oil for this engine and the average weather in mi city). I don´t drive the car a lot , maybe twice a month, so even tough that oil change was almost a year ago, I probably didn´t put more than 1200 miles on the car. Of course as soon as I discovered this i did fill it with the right oil, but my main concern is: might driving this car with another oil have caused any harm to the engine or something?