Not sure about oil but if the crankcase is vented the vent will be high enough it won't slosh out if upright.
Gas tank is sealed.. in fact true story... Campground used some 2000i generators for a halloween thing.. One at the station where I was kept stalling... They forgot to open the tank vent (A knob in the center of the gas cap).
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times