i say what the hell ever happened to .."motor oil is motor oil" they have diluted down the products so much that is hard to tell what you have any more ...I have that same motor so i will be going to the dealer for my oil when needed ...i would think being in Japan you would be in hog heaven when it comes to things like that......to answer your question i have no idea...but thanks for the opportunity to rant
Ken, it would be best to use a marine outboard oil instead of one made for car transmissions.. West Marine should have some and big stores like Wal Mart carry the stuff. it is mostly 80/90 .. I don't know which stores are available in Singapore, but if not a big store, then ask a local fisherguy where he gets his outboard gearcase oil.
80W90 is GEAR OIL, not motor oil guys and there is a BIG difference besides just the weight. For the record it is 80 weight at normal temp and thickens up to 90 weight when hot. As long as it is listed as a gear oil and therefore has the high pressure lubricants needed by gears it will be fine.