a Toyota owner’s manual in Australia for 2011 Toyota (with 2ZR-FE engine) has oil recommendations on page 429, https://toyotamanuals.com.au/docs/corolla-owners-manual-apr-10-dec-11/#page=430 Oil Grade: ____0W-20, 5W-20, 5W-30 and 10W-30: API grade SL “Energy-Conserving”, SM “Energy-Conserving” or ILSAC multigrade engine oil ____15W-40 and 20W-50: API grade SL or SM multigrade engine oil ____Then it has a chart with temperature ranges for different oil-weights (0W-20, etc) and principles: use 0W or 5W for starting in cold temperatures, and use 30 (or higher) “if the vehicle is operated at high speeds, or under extreme load conditions.” ____As explained earlier, I’m “trying to solve a mystery” and this information (Toyota recommending “only 0W-20” in USA, but giving options in Australia)* supports the CAFE-Standards theory, but may not prove it because… ____In an American forum, one critic of a CAFE-theory (he supports the FlowingSpeed-theory) claimed that engines in other countries are made differently (with different tolerances, etc) than in USA. He said that Toyota does this so in USA their cars will get better gas mileage. Would it be economically practical for Toyota to do this? Do they develop and manufacture engine-variations, so an “American 2ZR-FE” and “Australian 2ZR-FE” are different, so they require different oils for best protection? ____* The CAFE-regulations in USA state that the oil recommended in owner’s manual must be the same as the oil used in mileage tests, so if Toyota wants higher CAFE mileage (by using 0W-20 in tests) they must recommend the same oil (0W-20) in their owner’s manual.