I took my bike to the dealer for the 15,000 service. I told the service guy not to change the oil because I had done it myself 300 miles ago. Well guess what, yesterday I picked it up and they did the oil change anyway. Well I got a free oil change for next time from them. I had just changed it to M1 20-50 v-twin syn. They used the regular 20-50 HD oil. My question is can I just change the oil to M1 again without changing the filter (just drain it and pour in the M1). I know there will still be oil in the filter and I was wondering if this will affect anything. Thanks!!!