Hi, Newbie here first post. Please excuse any lapses in protocol. When I bought my 2011 RAV4 the sales manager mistakenly told me the V6 came with synthetic, it doesn't. The oil filler cap is labeled 5w30. Identical(?) Toyota engines of the same displacement in other models use synthetic. What can be the difference? After 1K or so I switched to Toyota synthetic, and now at 26,000 km I use 0W-20. Any comments or information? Thanks.