most important is making sure the oil level is maintained. Keeping it well ventilated so it runs cooler, maybe even adding a box fan to cool it, also extends the service interval if it is an air vs. liquid cooled unit. 100 hour service interval assumes a bunch of cold starts which is where the engine and the oil get the most wear. 100 hours continuous could be equated to all hiway miles on a car which extends the service life of the oil. For me, as long as it wasn't using oil, I would extend it to once a week, at least. (Manual may call for a higher temp oil for operating in high ambient temps. ) you might also consider a synthetic which also adds to the service life of the oil No doubt many will disagree but after a lifetime of working with all sizes of internal combustion engines I would be comfortable with extending the interval.