Was using Mobil 1 in my automobile and I decided to buy a brand new motorcycle living in Louisiana the engine of my motorcycle was air-cooled so thought synthetic oil would be a good up grade for my motorcycle engine, my owners manual said to put 1,000 miles for break-in, I put the 1,000 miles and changed my oil to mobile 1 after about 17,000 miles,I brought my motorcycle in for routine maintenance and to have my valves checked, then the mechanic came out to talk to me. That my shims were not worn but just polished he wanted to know what motor oil I was using I said mobile 1 he said to drain my oil,and put non synthetic motor oil to complete the break-in period on my bike.