06 Sienna at 230k miles with original Iridium spark plug.

It is recommended for replacement at 120k miles in the manual. I did not change it for two reasons: 1. there is no signaficant drop in gas efficiency. 2. It is time consuming for replacing spark plugs in 06 Sienna (the back three spark plugs). I did open one of the cyclinder, the spark plug looked normal at 160k miles or so.

所有跟帖： 

• Gas Mileage 是最直观的reference，去除天气影响，若其有大变化，车子一定有问题 -mountrobson- ♂ (0 bytes) () 12/15/2022 postreply 13:58:31

• 　我每次加油都记下加油量和当时的里程，就能算MPG了 -MoonRiverMe- ♂ (33 bytes) () 12/15/2022 postreply 17:24:53