I have 2 Exmark Lazer Z HP's with 23 HP Kaw engines. One I just bought from a guy in December who says he always has run synthetic oil in the engine since he has had it for the past couple years. What you do think about doing that? Any advantages or disadvantages? My old mower has 1300 hours on it now. Do you think it would harm it if I switched it to synthetic now? I have always uses SAE 30 wt in the engine and have not had any issues for 5 years. Just wanted to see what you all thought about this. I hate to change somthing that has been good to me for this long. Thanks for the response.