Excessive oil usage?

[John Harper]

During a recent 3 week cruise of 533 NMs from New Bern to Charleston and back via the ICW, I put 97 hours on a 6-year old 27 hp Yanmar 3GM30F that has operated 650 hours. It seemed like I had to add a lot of oil during the trip.The total oil capacity is about 2 3/4 quarts and the effective capacity is about 1 3/4 quarts. I probably added a dipstick's worth of oil, maybe a quart and a half or quart and three quarters. The rated 1 hour output of the engine is 3600 rpms, with a 3400 rpm continuous output. Most of the time I ran the engine at about 2800, or about 80 percent of its capacity. The engine temperature stayed about where it has always been. Although I did notice white exhaust smoke from time to time.The oil change interval is 150 hours and I've always followed it. That interval suggests the engine may have used an excessive amount of oil during the 97-hour cruise. Or it may mean that I used almost a season's worth of the engine in 3 weeks and oil usage was about right. Does anyone have some thoughts on this?Thanks.

 

[Bob Howie]

Could be rings, but...

First off, less than 2 qts of oil in nearly 100 hours of use doesn't sound like too much of an oil problem to me. The main reason an engine will burn oil is cylinder wear or a ring problem, either stuck or broken. 650 hrs. on your engine doesn't sound like too much time and if you have been following your oil change regimine, then it's not likely you're getting any excessive cylinder wall wear.I'm not that familiar with the 3GM30F, but, if you have an oil filter, change it out now and using an oil filter opener (looks like a can opener for oil filters), but it open and examine the filter material to see if you have an noticeable metal bits in it. You might have some, but if you have lots, then you have a problem.You can have oil analyzed. Quite common in the aviation industry and you can get it done outside aviation as well. You typically will need a number of oil analysis's in order to get a good approximation of what's going on inside your engine. You can graph it on M/S Excel and the folks who do the analysis can tell you which types of metals they are seeing and then those metals can correspond to the materials inside the motor, thus giving you an idea of what's wearing.However, I'm not thinking you have much of a problem because less than 2 qts in 100 hrs isn't all that much; engine temp stayed about normal throughout the entire trip and a little white smoke occasionally, not continuously, and not blue smoke all the time would not indicate excessive oil burning.I may be wrong, but I think the time you spent running the engine just used that much oil naturally. Just my opinion, tho.

 

[Clyde Lichtenwalner]

Not excessive

Would you be upset if your car used the same amount of oil in 6,000 miles? Figure it this way. 2,800 rpm is the speed a typical 4cyl automobile turns at 60 mph. In 100 hours at 60 mph you would cover 6,000 miles. Sounds well within the normal range to me.

 

[Miles]

On mine...

On my 3GM30F (4 years old, 500 hours) I use maybe 1/2 a quart of oil every 100 hours. I change the oil every 100 hours and usually run at 2800 RPM just like you. This is just for comparison purposes, your milage may vary ;.) I agree with the other posters that it doesn't sound too bad.P.S. I'm using Delco 10-40, I suppose viscocity might make a difference here.

 

[Bob Howie]

Hey, Clyde...

That's a great way to apply a rule of thumb to bring things into perspective. Best I've seen yet!! I just wish my car only burned 1.5 qts in 6,000 miles!!