Briggs' chart shows SAE30 from 4C to the top of the chart at 49C. However I think the use of SAE40 in really hot conditions would probably reduce oil consumption without causing problems. The issue Briggs seem to be concerned about, is difficulty spinning the engine fast enough to start it, in cold weather. You can't rely on the operator to change oil seasonally, so they would be in danger of getting customer complaints in winter if they authorised SAE40.
Agreed, but only advisable if oil consumption has increased enough to be a problem. Wouldn't go higher than SAE40, even then. Initial lubrication on startup can suffer from the use of a heavier oil, in a splash-lubrication engine. And that's when a lot of the wear occurs.
Multigrade can be one solution to the spin speed issue. At the cost of increased consumption, as we know.
