[1speedbike]

For the 135i there are 4 approved non-BMW oils listed on the BMW USA website, including both 5w-30 and 0w-40. The list includes mobil 1, castrol, penzoil, and one more brand, all the special full-synthetic euro blend oils. Though these are approved in the US, all of these oils are imported from Europe specifically for European cars because we apparently manufacture crap oil in the US haha. But in oz there might be oils available and approved that we don't get. But I'd say either weight is safe. 5w 30 is less viscous cold, but more viscous warm, and 0w 40 is more viscous cold and more viscous warm. Some people think this makes different weights suited for different seasons (based on the ambient temperatures since the heat thins oil) but most people will probably say it doesn't matter.