i have a 1977 yanmar YSB8 in my sailboat; I had been using up a small stash of old Delo 30W rated CF that came with the boat, but I haven't been thrilled with starting performance in cold weather. the engine starts great in the summer when it's over 50F or so (and starts very easy in our 95F heatwaves!), but in the winter we get down into the low 30s and it's sluggish to get it going. this is a flat-tappet, raw water cooled engine and it runs cold; operating temperature is set by a 140F thermostat. there is no filter, only a stacked-plate strainer.
I tracked down a copy of the owner's manual for this engine, and it is hopelessly out of date, specifying single-weight oils for the most part:
my concerns are as follows:
1) need to use an oil available in quarts, ideally off the shelf. storage is tight and its a lot easier to stow quarts.
2) suitability for wet-clutch. the tranmission uses a single disk clutch and the manual calls for using the same oil as in the engine; i'd like to continue that for simplicity's sake. in reading i've been lead to believe that the friction modifiers found in API CG and later specs are not acceptable for the clutch.
3) ease of starting in cold weather. the only straight weight oil i've found locally is the 30W; I'd like to try a 20W l but i can't get it.
delo 400 SDE or rotella T4 15w40 look OK, but i'm not sure it will be much of a difference from the straight 30w in viscosity at starting temp & i'm a little worried about the wet clutch with the CK rating.
if I have to order in oil, would Amsoil's ASF Synthetic Small Engine 10W40 be a decent choice? it looks good in terms of viscosity, it meets CD/CF and it's OK for the wet clutch. but i keep reading on forums that I shouldn't use synthetic in the Yanmar.
or I could stick with the delo 400 30w and just put up with the hard starts; it's only two or three times a year.
i'm getting a bit confused trying to figure out which oil i should try. thoughts?
I tracked down a copy of the owner's manual for this engine, and it is hopelessly out of date, specifying single-weight oils for the most part:
my concerns are as follows:
1) need to use an oil available in quarts, ideally off the shelf. storage is tight and its a lot easier to stow quarts.
2) suitability for wet-clutch. the tranmission uses a single disk clutch and the manual calls for using the same oil as in the engine; i'd like to continue that for simplicity's sake. in reading i've been lead to believe that the friction modifiers found in API CG and later specs are not acceptable for the clutch.
3) ease of starting in cold weather. the only straight weight oil i've found locally is the 30W; I'd like to try a 20W l but i can't get it.
delo 400 SDE or rotella T4 15w40 look OK, but i'm not sure it will be much of a difference from the straight 30w in viscosity at starting temp & i'm a little worried about the wet clutch with the CK rating.
if I have to order in oil, would Amsoil's ASF Synthetic Small Engine 10W40 be a decent choice? it looks good in terms of viscosity, it meets CD/CF and it's OK for the wet clutch. but i keep reading on forums that I shouldn't use synthetic in the Yanmar.
or I could stick with the delo 400 30w and just put up with the hard starts; it's only two or three times a year.
i'm getting a bit confused trying to figure out which oil i should try. thoughts?
