After a lot of research I finally decided on a Exmark 72 inch diesel , I am a retired farmer from Illinois . As a farmer I needed a side hustle so I started mowing cemeteries, which lead to residual properties, which led to me deciding I was making more money mowing then I was farming . I have been a loyal Kubota diesel mower customer for over twenty years , and even though I believe the reliability of the Kubota is top notch , their deck and quality of cut is very poor and I finally had enough. I have used the Exmark about 5 hours so far and I must say I have been very impressed. On a new diesel mower I always changed oil first time at 50 hours and then every 100 hours , and I always use shell rotella 15-40 in my tractor and Mobil delvac 1300 super 15-40 which is a synthetic blend in my diesel mowers . When would you suggest I change oil first time and can I use my oil or should I stick with the Exmark oil ? Thanks so much