Probably 15-40 or 20-50 oil. I tend to stick with semi synthetic rather than wholly synthetic. Thin slippery synthetic diesel oils were made for smaller high speed motors like modern Japanese 4WD diesels with small bore oil journals. An older design slow revving marine diesel can do with some good quality courser mineral oil in the mix.
Of course, this is opinion only. Any 20-50 diesel sold in Oz will satisfy or exceed industry standards. Just change the filter each time and change the oil a couple of times per year.
Depending on the engine's angle, the dipstick won't be accurate and some 'old' oil will sit at the back of the sump. All depends on where the he sump plug is, and whether you're using a suction pump to drain the oil.
Yeah like Bushdog said, change a few times a year, I think regular changes for a diesel are way more important than the type of oil whether synthetic or not. Diesels are dirty motors with their combustion by by products.
One thing a mechanic told me about synthetics that I did'nt realize is that they can tend to slip past oil seals easier than mineral, so I guess that is worth keeping in mind.
From a mate that owns his own diesel injection business for 30+ years when he rebuilt my Perkins.
Single weight 15-30 (15 preferable, but maybe cold climates such as Tasmania 30w) non synthetic.
Modern hitech/turbo - then whatever the manufactures says.
Change a couple of times a year? How many hours do you do to warrant that?
My manual says change the oil and filter every 100 hours. That was based on oil made in the late 70s early 80s.
With modern oils and new filters I can't see there is a need to change it any more often than the manufacturer requires.
Select to expand quoteMorningBird said..
Change a couple of times a year? How many hours do you do to warrant that?
My manual says change the oil and filter every 100 hours. That was based on oil made in the late 70s early 80s.
With modern oils and new filters I can't see there is a need to change it any more often than the manufacturer requires.
I have heard its not the hrs that count, its the time the oil spends in the engine . It gets corrosive the longer it stays in there .
Select to expand quoteSandS said..MorningBird said..
Change a couple of times a year? How many hours do you do to warrant that?
My manual says change the oil and filter every 100 hours. That was based on oil made in the late 70s early 80s.
With modern oils and new filters I can't see there is a need to change it any more often than the manufacturer requires.
I have heard its not the hrs that count, its the time the oil spends in the engine . It gets corrosive the longer it stays in there .
True, and keeping the oil clean is great for engine life. But oil gets impurities from use. Clean oil in the sump will stay clean for a long time without use.
Oil and filters are a cost and changes often messy. My pump broke a couple of years ago spraying black oil everywhere.
MB's engine is now 33 years old and has had oil and filter changes approx every 100 hours, usually every 18 months or so. It starts immediately, doesn't blow smoke, is economical and runs well. 33 years with many more to go is pretty good. Spares availability will kill it before it's oil.
I maintain oil and filter changes in accordance with the manual will give a good engine life most economically.
Select to expand quoteSandS said..MorningBird said..
Change a couple of times a year? How many hours do you do to warrant that?
My manual says change the oil and filter every 100 hours. That was based on oil made in the late 70s early 80s.
With modern oils and new filters I can't see there is a need to change it any more often than the manufacturer requires.
I have heard its not the hrs that count, its the time the oil spends in the engine . It gets corrosive the longer it stays in there .
Motor Oil can be or is hygroscopic, it absorbs moisture and moisture breaks down additives in the oil and also causes corrosion. It may be claimed that the more additives in oil, the higher possibility it has of absorbing moisture.
I have an oil can in the shed that I put left over motor oil in and in no time it goes milky. I have an identical can that contains machine oil and it is never milky
Select to expand quoteJolene said..SandS said..MorningBird said..
Change a couple of times a year? How many hours do you do to warrant that?
My manual says change the oil and filter every 100 hours. That was based on oil made in the late 70s early 80s.
With modern oils and new filters I can't see there is a need to change it any more often than the manufacturer requires.
I have heard its not the hrs that count, its the time the oil spends in the engine . It gets corrosive the longer it stays in there .
Motor Oil can be or is hygroscopic, it absorbs moisture and moisture breaks down additives in the oil and also causes corrosion. It may be claimed that the more additives in oil, the higher possibility it has of absorbing moisture.
I have an oil can in the shed that I put left over motor oil in and in no time it goes milky. I have an identical can that contains machine oil and it is never milky
No doubt oil does go off with time, especially when it gets impurities in it from use.
The point I am trying to make is oil changes more frequently than recommended will ensure the oil will be clean, but it is not likely to materially increase engine life, it costs money and time and increases the risk of spills and mess.
Select to expand quotecavalier32 said..
For a Bukh 20 hp, should it be full synthetic or thereabouts.
Gary
Definitely not synthetic. Stick with what the manufacturer recommends. Preferably mono 30 grade but any of the cheap multi grades will do. 100 hours or every six months, which ever comes first. If your filter is hard to get to, change that once a year or every second change of oil. If you are doing lots of hours then an oil change once a fortnight is fine. Oil is the cheapest item you will put in your boat.
Old engines use old style oil. Flat tappet engines need at least 1200ppm of ZDDP
My Bukh 10 hp manual definitely states that mono grade 30 is the oil to use. I get it from Repco.
Thanks for all your advice it has been very helpful.
Great sailing everyone, hope to see you out there
