Having spent hours trying to find out the real skinny on gearbox oil, I found an online Yanmar manual that is much more complete and detailed than the one that came with my engine. Link as follows:
http://www.yanmar.no/theme/yanmarpo...eration-manual/YM-OM/0AYMM-EN0023_English.pdf
Specifically, one is to use MARINE gear oil, API CD or higher, KM2P-1 (S), (G), or (GG), SAE 20 or 30. Don't bother looking at the automotive store, as I checked several.
On my SD20 gearbox, attached to the 3YM30 engine, the gear oil is checked without screwing the dipstick in; the high mark is just above the base of the dipstick, and the low mark is essentially the base of the dipstick.
BTW, this manual covers several of the 3Y- - engines.
http://www.yanmar.no/theme/yanmarpo...eration-manual/YM-OM/0AYMM-EN0023_English.pdf
Specifically, one is to use MARINE gear oil, API CD or higher, KM2P-1 (S), (G), or (GG), SAE 20 or 30. Don't bother looking at the automotive store, as I checked several.
On my SD20 gearbox, attached to the 3YM30 engine, the gear oil is checked without screwing the dipstick in; the high mark is just above the base of the dipstick, and the low mark is essentially the base of the dipstick.
BTW, this manual covers several of the 3Y- - engines.