I just went to change the oil on my new Lazer (25/60 Kohler) as recommended after the first 5 hrs. I was going to just change the oil and not filter as it says to change the filter every other change. However, the manual states to change oil and filter after the first 5 hrs. Is this critical, or can I get away with just the oil change? After this initial change I was going to change it yearly (homeowner use) and change the filter every year also. Is it all right to change the filter every time if it is only once a year that I change oil? Thanks.