If you want to run synthetic, then go to Amsoil's website. They have a product that is equal to straight 30 weight.
Oil.... as a subject matter... is as personal and volatile as politics and religion. Therefore, I will not attempt to sway you one way or the other. There is no filtration on your motor. As such, the only way to protect the engine is to change out the oil every 25 hours at the maximum. If you were running in very dusty conditions, then perhaps every 10 hours would be more advisable. Using a synthetic oil does not change any of that because both types of oil will get equally contaminated under the same operating conditions.