1. Do any of you guys know when you should change Iridium spark plugs in your boat?
2. I have a 2000 Lund pro-v I have a set of 4 dummy lights incased in a round 3 circle. I must be and idiot because I can figure out three of them but the one on the bottom looks like a canister with a plug? Is that supposed to be the injection oil level? If so is that reading the one in the boat or on the motor?