I have a 1990 150proV and I'm trying to figure out which way to adjust the air adjust screws on the top of the carbs to make the motor run a little leaner. The motor is running good but I'm getting a pretty good oil slick in the water when the motor is idling and the plugs are also a little more oil than they probably should be. My maintenance manual just gives the starting point of 3/4 turn out on the STBD sides and 1 1/4 turns out on the PORT but doesn't say which way to go from there to make it run richer or leaner. Also, if anyone knows for sure, am I better off letting this old motor run a little rich. I'm just trying to get maximum fuel and oil efficiency and trying to pump as little oil into my fishing waters as possible. Thanks.