So, how long between oil changes when you go with synthetics?...in my case Royal Purple. I put in Royal Purple 3,000 miles ago, and now my FJ oil change light ("Maint Reqd") comes on. I can live with the fact that the light is annoying. Anyone have input on how long the Royal Purple holds up? I seem to recall someone mentioning that RP doesn't start breaking down until 11,000+ miles, although I think I'd want to change it much earlier than that just to change out the crud.