OK just done gearbox oil change on my gen 3 and a friend's gen 4 prius. Question.? Is toyota ws oil synthetic or just mineral. On a side note this was my second change of my gen 3 at 104,000 miles and the first change of the gen 4 at 115,000. The gen 4 had notably cleaner oil than gen 3 which I thought was odd, it literally came out as clean as the new stuff I put in. Posted via the PriusChat mobile app.
That's very interesting: the fourth gen transaxle is a radical change in design, has two shafts side-by-side I think. Maybe inherently cleaner running, less wear?
