What is "normal" oil consumption?

Nov 21, 2007
631
Beneteau Oceanis 34 Kingston, WA
What is the rate of lubricating oil consumption for a small diesel engine?
We have a Yanmar 3YM30 with a little more than 500 hours on it. This season, especially lately, I have been noticing that the oil level is down on occasion when I check it. I know that it's possible that one factor could be the the amount of time that we have used it this summer... I don't know the exact number of hours this year vs. prior years for us, but I will try to check that tomorrow. The consumption that I'm seeing is not an alarming amount, just that over the course of time, the oil level is not where it should be. So, I add 8 - 12 oz. at a time to get it back up to the level on the dipstick where I want it.
How much oil do you add, and how often? How much oil should I expect an engine to use under normal conditions?
 
Oct 1, 2007
1,856
Boston Whaler Super Sport Pt. Judith
What is the rate of lubricating oil consumption for a small diesel engine?
We have a Yanmar 3YM30 with a little more than 500 hours on it. This season, especially lately, I have been noticing that the oil level is down on occasion when I check it. I know that it's possible that one factor could be the the amount of time that we have used it this summer... I don't know the exact number of hours this year vs. prior years for us, but I will try to check that tomorrow. The consumption that I'm seeing is not an alarming amount, just that over the course of time, the oil level is not where it should be. So, I add 8 - 12 oz. at a time to get it back up to the level on the dipstick where I want it.
How much oil do you add, and how often? How much oil should I expect an engine to use under normal conditions?
I find it difficult to measure the real dip stick level on my Yanmar. The engine is so air tight that in order to arrive at an accurate reading I must loosen the filler cap, let the engine sit for a few minutes, then gently insert the dipstick. Even then, the gaskets on the dipstick can force the oil level down in the the tube, resulting in a faulty reading.
 
May 17, 2004
5,031
Beneteau Oceanis 37 Havre de Grace
What is the rate of lubricating oil consumption for a small diesel engine?
We have a Yanmar 3YM30 with a little more than 500 hours on it. This season, especially lately, I have been noticing that the oil level is down on occasion when I check it. I know that it's possible that one factor could be the the amount of time that we have used it this summer... I don't know the exact number of hours this year vs. prior years for us, but I will try to check that tomorrow. The consumption that I'm seeing is not an alarming amount, just that over the course of time, the oil level is not where it should be. So, I add 8 - 12 oz. at a time to get it back up to the level on the dipstick where I want it.
How much oil do you add, and how often? How much oil should I expect an engine to use under normal conditions?
Our 3YM30 burns some as well. For comparison, here is what the dipstick looked like at the start of the season with 343 hours -
1603882619470.jpeg


And last weekend with 410 hours -
1603883546464.jpeg
 

Johnb

.
Jan 22, 2008
1,419
Hunter 37-cutter Richmond CA
What is the rate of lubricating oil consumption for a small diesel engine?
We have a Yanmar 3YM30 with a little more than 500 hours on it. This season, especially lately, I have been noticing that the oil level is down on occasion when I check it. I know that it's possible that one factor could be the the amount of time that we have used it this summer... I don't know the exact number of hours this year vs. prior years for us, but I will try to check that tomorrow. The consumption that I'm seeing is not an alarming amount, just that over the course of time, the oil level is not where it should be. So, I add 8 - 12 oz. at a time to get it back up to the level on the dipstick where I want it.
How much oil do you add, and how often? How much oil should I expect an engine to use under normal conditions?
In my 3QM I usually do not add oil between oil changes which is annual event. Run time is 50 to 80 hours typically. If you have a run time meter you should log all maintenance and fuel against the engine hours.
 
Dec 25, 2000
5,702
Hunter Passage 42 Shelter Bay, WA
Never need to add oil to our 1991 4JH2-TE between oil changes, which has a bit over 2000 hours.
 
May 12, 2004
1,502
Hunter Cherubini 30 New Port Richey
Have a 3ym20 with just over 800 hours. Change oil every 125 -150 hours. Have never had to add oil between changes. Knock on wood.
 
Apr 5, 2009
2,774
Catalina '88 C30 tr/bs Oak Harbor, WA
Unless it is a 2-stroke gas engine it should not burn any oil. A properly running 4-stroke engine should not need any added oil between normal recommended oil changes. Most often the problem is a small leak. If it is truly burning it and not leaking, the culprit will be either worn rings or bad valve seals and/or guides. That is not to say that it will not run for many years with a leak or burning oil but it is a sign if needed work in your future.
 
Nov 21, 2007
631
Beneteau Oceanis 34 Kingston, WA
I find it difficult to measure the real dip stick level on my Yanmar. The engine is so air tight that in order to arrive at an accurate reading I must loosen the filler cap, let the engine sit for a few minutes, then gently insert the dipstick. Even then, the gaskets on the dipstick can force the oil level down in the the tube, resulting in a faulty reading.
I find the same thing. Measuring with he dipstick takes two attempts, remove; nothing on it, reinsert and remove a second time to check oil level. The first time I saw "nothing" on the dipstick, the engine was absolutely new, I had a short heart attack and thought it might be a good idea to put the stick back in and check a second time... had oil that time, whew!
 

NYSail

.
Jan 6, 2006
3,048
Beneteau 423 Mt. Sinai, NY
Old boat with 3hm35f had 10 years never had to add and with new 4jh4e same so far after 4 seasons. If they burned oil it was so negligible I could not tell..... check oil every time before I head out. If this is a new event you should check a bit further. Is there smoke from exhaust lately?
 
May 17, 2004
5,031
Beneteau Oceanis 37 Havre de Grace
Old boat with 3hm35f had 10 years never had to add and with new 4jh4e same so far after 4 seasons. If they burned oil it was so negligible I could not tell..... check oil every time before I head out. If this is a new event you should check a bit further. Is there smoke from exhaust lately?
Not for mine. Been that way from the factory, and there’s no noticeable smoke. I don’t really need to add oil during a season. I sometimes do just to bring it back closer to the full line, but it’s still well above the empty line.
 
Nov 21, 2007
631
Beneteau Oceanis 34 Kingston, WA
No noticeable smoke from mine either. There might be a little discoloration around the exhaust outlet, but how would you know if that was from engine oil or diesel? I checked my log book, and my guesstimate is that I've added about 12 oz. of oil in a little more than 110 hours of use this summer.
 
  • Like
Likes: jssailem
May 24, 2004
7,129
CC 30 South Florida
Normal is between the lines; should not have to add any oil between yearly oil changes. If you are using excessive oil make sure all the breathers are clear and move to a higher grade oil like 15W40.
 
Nov 21, 2007
631
Beneteau Oceanis 34 Kingston, WA
I use 15W40, and I try to keep everything on, attached to, and near the engine absolutely spotless (I used to race cars for a hobby :cool: ).
 
Nov 22, 2011
1,192
Ericson 26-2 San Pedro, CA
FWIW, this is from the Yanmar GM/HM Workshop Manual (p. 45):

"All engines will consume a certain amount of oil as a lubricating
and cooling agent. The amount depends on engine
use and engine condition. During the engine break-in
period, the engine consumes more oil while the piston
rings seat in the cylinder bore. Engines with high hours of
use may bum more oil due to worn engine components.
Engines generally consume more oil at higher engine
speeds."
 
May 24, 2004
7,129
CC 30 South Florida
I use 15W40, and I try to keep everything on, attached to, and near the engine absolutely spotless (I used to race cars for a hobby :cool: ).
Don't know of any small diesel engine race cars. I used to race motorcycles but have found no correlation with running auxiliary marine diesels. The oil level should be checked at similar times under similar conditions for a fair comparison of the level between a previous and the current check. It is hard to gauge whether 8-12 ounces is normal without knowing the number of hours the engine ran in between. If you want to get an indication of the amount of oil blow-by past the piston rings remove the oil cap while the engine is idling and hover the palm of your hand over the opening. In a fairly new engine you should just feel some slight pulsating pressure where in a worn engine you will feel a strong pulsating thump. To which end does your engine lean to? If you have not noticed any oil leaks and the back pressure coming out of the oil filler opening seems normal I would say your consumption should be normal.
 
Nov 21, 2007
631
Beneteau Oceanis 34 Kingston, WA
@Benny17441... not necessarily a direct correlation between the hardware, but the way I approach maintenance and monitoring is the same. Cleaning, and keeping things clean, is visually inspecting. I would have noticed any significant leaks, there haven't been any. I don't use the cheapest supplies and consumables that I can find. I try to be diligent and consistent my checks and record keeping, and I like my results to be repeatable and consistent as well. I did mention 110 hours of engine time for 12 oz. of oil added in my previous post.
 
  • Like
Likes: jssailem