No, no, and no.<br /><br />Merc inline sixes are very octane sensitive. In fact, merc switched to lower compression pistons in later years when gas got crappier.<br /><br />93 octane of inlines. Especially the 140 and 150's.<br /><br />Also 93 octane for any merc hipo motors.<br /><br />Also if you let the gas sit for any length of time I would use 93 in anything else as gas can lose octane very quickly in sunlight or high heat conditions. Also the shelf life of gas is only around a month. To me I'd rather spend an extra buck on gas on not worry about it melting my $$$$ motor.87 octane for any outboard.