I have a 1988 Mercruiser, Alpha 1 (With a 305)(5.0). Upon looking at changing the gear oil, i only seem to see a botton drain plug, and cannot seem to see a vent plug. I have had many outboards, but this is my 1st inboard. I wanna change the oil, but am i just not seeing the vent plug, or is there just not one there. Also i have always used the synthetic merc oil, and the guy that had this boat before me, use i think he said "red dot?" or something or other. Just wondering on which oil would be better.
