Ok, today I was changing my oil and when I was done. I noticed that the oil pan I had used to drain the oil had small pieces of metal. Does this mean my pistons are rubbing? It had been about 3500 miles since I changed my oil. My car just hit 40,000 miles. I always use a K&N Gold oil filter and Mobil 1; 10 30 oil. Is the oil I'm using to thin or is there something else I'm missing or I should do. I would appreciate your input, thanks.