I agree with Bror Jace on the 15W40 HDM(E)O. That is all i used in my 6.5 Hp Briggs while I was down in the Panama area for two years. I would dump the oil into a clean plastic can then run it thru a coffie filter and I found lots of metal particals when using 30W and very little metal using 15W40. In a aircooled splash lub'ed engine I think any good 15W40 Dino oil should be great in the Hawaii heat. DaveJ