I just purchased an Exmark Commercial 30 with a Kawasaki FJ180v KAI. I will be running it in temperatures from 75F in the beginning of the season up to 100F in the middle of the season. I would like to buy the best possible oil available to protect my $1800 dollar investment. The manual recommends either a 10w30 or a sae30. Any recommendations or advice would help. The dealer suggested royal purple 10w30 but I have read before that 10w30 is more of a cold weather oil. Any suggestions would be appreciated.