How do you know the year model, My boat has model J150STLESB , SERIAL# R08581859 But I don't know the year model. I had one reply that said it was a 1990. Is this correct? It has an oil injection system on it and should I remove and go to mixing with gas? I have heard stories about problems with older units. I have just bought this boat and would like to keep it running for awhile and Have very history on this motor. The motor at this time is running very well.