Hi Buckets, welcome to Outdoorking.
So far as oil is concerned, I use what the engine manufacturer says I should use: not his brand of course, but the same specification. For your Vanguard, Briggs say use an SAE30 oil, rated for automotive service SJ or a later specification than SJ. You can buy the stuff in quite a lot of automotive shops, but it will probably cost a bit more than the multigrade that they mostly sell. Do not use multigrade oil, or you'll use a lot of it, in the hot Australian climate. Straight SAE30 has been the Briggs specification for engine oil for many years, and they are correct, multigrade oils are consumed quickly in their engines.
