Have a 120aq volvo penta engine coupled to a Chrysler 270 drive. Bought boat late in season last year ran it only for about 10 minutes, water pump blew. Stored for winter, got out this summer and fixes everything. Drained oil from drive. It is engine oil, a multi-weight it seems . Maybe a 10/40. I cannot find what goes in it. Does avyone know the correct lube that it takes. I know it is 5G rated. Thanks. It is a 1978 setup.