Dino vs synthetic

[finefurn]

I've got a 1989 Westerbeke 12b2 that I normally put 50 hrs a year on. I've only owned the boat for 3 yrs and I have no idea what oil the previous owners used in it. This is my first experience with a marine diesel and I was told by someone that supposedly knows, is that you should only use dino grade in an old diesel. Hence I've used Shell Rotella T4 in it the last 2 years. Given the low usage would I be inviting troubled if I switched to a synthetic blend. Can these 2 different oils be mixed. What's the advantage of one verses the other

[sailorboy1]

There are old long threads here about. Personally i think a blend would be fine. But I also think regular oil is fine and if you going to do the normal NE change the oil every year and only do 50 hours/year there isn't really any plus to a blend.

[Jammer]

Check the recommendations from Westerbeke and follow them. Chances are they recommend a CC rated oil which most modern synthetics are not. For a diesel you want an ashless disperant oil


For most people the whole point of the exercise with synthetic oils is that they are less susceptible to shear. Lubricating oils fail due to viscosity loss as a result of shear, combined with accumulated contaminants. Synthetic oils provide better lubrication for longer, allowing either less engine wear or an extended drain interval, take your pick. They also allow a higher operating temperature which allows for higher performance engine designs


It is really rare to encounter a runout engine where the life the engine could plausibly have been extended through the use of a different engine oil or more frequent drain intervals. Engines get scrapped or overhauled for lots of reasons and accumulated wear on internally lubricated parts is rarely one of them


More common are things like seal and gasket failures, oil exhaustion, lack of any sort of regular oil changes at all, critical component failures i.e. timing chain, oil pump, broken rings, overheating due to lack of coolant, lack of coolant flow, etc., accumulation of solvable problems e.g. injectors, injection pump, manifold cracks, main seals

[Compass790]

Oil arguments are like guns, boats, cars etc. Can go on forever & everyone has an opinion.
jammer makes a lot of good points.


You can use either synthetic or dino as long as it meets or exceeds the API std.
Best not to mix different types frm different manufacturers but they do have dino/synthetic blends.
If I had a turbo, think I would spring for syn but perfectly happy with dino in our 1980 naturally aspirated yanmar.
Dont sweat it.

[C420sailor]

I run the Shell T4 in my 30B3. I don’t see the need for synthetic in these engines.