Oil Burn Rate - CAT 3116

[mainshiptim]

Hello,

Any feedback on whether my oil burn rate is high, normal, or low?

I calculated my engine oil burn rate to be approx 1 quart every 23 engine hours.
Mainly cruise at 7-8 knots.
Total engine hours is 2161
2000 Mainship 390

Thanks, - Tim

 

[luna]

In the Cat Operation & Maintenance Manual there is likely a paragraph near the back of the book titled Overhaul. In there you should find some kind of oil burn rate that you can compare to your present burn rate in order to judge how close to overhaul you are.

You should also heed whatever the current Cat recommendation is on the oil for this engine.

 

[DavidM]

Your oil burn rate is high, but most engine manufacturers give high rates to cover their ass, so be aware.

You are running at 7-8 kts which is a low power rate which leads to sooting and a glaze forming on the cylinder walls which leads to oil being lost.

Try running for 6-8 hrs at 200 rpm off of top. That will often clean up the glaze and oil loss.

If that works, run the engine hard for a half hour every eight hours of low speed running to keep it clear.

David

 

[hmason]

I had twin 3116s on a 46' GB. I ran around 9 to 10kts constantly. Engines used almost zero oil. Probably added 1 quart per engine from CT to FL.

 

[High Wire]

Hello,

Any feedback on whether my oil burn rate is high, normal, or low?

I calculated my engine oil burn rate to be approx 1 quart every 23 engine hours.
Mainly cruise at 7-8 knots.
Total engine hours is 2161
2000 Mainship 390

Thanks, - Tim

What is the RPM at that cruise speed?

 

[Mac2]

Can't remember the post, but someone mentioned if you fill the oil to the top mark of the dipstick, this could cause excess oil burn because the dipstick is designed for an engine that sits level. Can anyone confirm this?

 

[mainshiptim]

What is the RPM at that cruise speed?

I run at 1600 RPM normally and WOT every 6 hours for a couple minutes

 

[Mac2]

Do you fill to the top line of the dipstick?

 

[mainshiptim]

Your oil burn rate is high, but most engine manufacturers give high rates to cover their ass, so be aware.

You are running at 7-8 kts which is a low power rate which leads to sooting and a glaze forming on the cylinder walls which leads to oil being lost.

Try running for 6-8 hrs at 200 rpm off of top. That will often clean up the glaze and oil loss.

If that works, run the engine hard for a half hour every eight hours of low speed running to keep it clear.

David

Good information. Thank you David

 

[mainshiptim]

In the Cat Operation & Maintenance Manual there is likely a paragraph near the back of the book titled Overhaul. In there you should find some kind of oil burn rate that you can compare to your present burn rate in order to judge how close to overhaul you are.

You should also heed whatever the current Cat recommendation is on the oil for this engine.

Great I’ll call them. Thanks

 

[mainshiptim]

Do you fill to the top line of the dipstick?

Yes sir

 

[Mac2]

Yes sir

Me too. I am also having the same issue as you (twins burning oil at the exact same rate). I am going to leave the oil at the halfway point of the dipstick and see if I notice a difference.

 

[Mac2]

PS I have CAT 3208 NAs

 

[mvweebles]

I realize zero is good, but this engine probably holds 5 gallons - 20-quarts. I wouldn't worry too much at that burn rate. I would track it and look for changes. Definitely keep track of engine oil analysis at regular intervals.

Peter

 

[heysteve]

PS I have CAT 3208 NAs

Just FYI... there was a Cat bulletin in April 1985 that said to reduce the total capacity for the NA to 13 quarts including a filter change. If your boat is older than that, it's possible your dipstick is not marked properly.

 

[tiltrider1]

First I have Cat 3208’s not 3116’s. I drained my oil and then added 4 gallons as the manual requested. I then noted the level on the dip stick. Oddly the level was different between the two engines. I then noticed I went through a gallon of oil in 50 hours per engine. Due to a hectic travel schedule I paid a CAT mechanic to do an oil change. When I got home I checked the oil level and it was Lower than what I thought was right. The mechanic insisted it was correct and that I had been overfilling the engine. He said it wasn’t an issue the engine would just burn up the excess oil and that I would end up at the right amount.

After doing some research I found that there are different sized oil pans for 3208’s. I just have never been able to figure out what CAT has to say about the oil pans on my boat with the engine being angled. As such I keep a close eye on oil level. I probably waste oil but I never heard of an engine failure do to excessive oil changes.

 

[luna]

The same Cat Operation and Maintenance Manual referenced earlier will likely have about 1/2 way through the 70+/- pages, instructions on how to calibrate the dipstick.

Which go something like this.

Tuesday afternoon drain all the oil from the sump, leave the plug out. Pull the filters.
Wednesday at 10:00 am put xx quarts of oil in the valve cover oil filling port after you put on new filters and installed the plug.

After lunch install and remove the dipstick. That is now the new add level. Check it a few time and mark (a punch or hacksaw) the dipstick with the add mark.
Now add yy quarts of oil and mark the full level. You’re done.

 

[luna]

All engine fluid volumes are listed in the O&M Manual and in addition to that on my 3408s (which can also have different oil pans) there is a large label on the port side of the oil pan that lists Oil Refill Capacity. 23 Gal. Oil filter PN. Oil change interval 500 hrs, one year or 7000 gal of fuel consumption. Plus the same kind of info for coolant.

Have a look you might have one as well.

 

[mainshiptim]

I realize zero is good, but this engine probably holds 5 gallons - 20-quarts. I wouldn't worry too much at that burn rate. I would track it and look for changes. Definitely keep track of engine oil analysis at regular intervals.

Peter

That makes sense to look for ongoing changes

 

[mainshiptim]

Me too. I am also having the same issue as you (twins burning oil at the exact same rate). I am going to leave the oil at the halfway point of the dipstick and see if I notice a difference.

Makes sense

 

[mainshiptim]

The same Cat Operation and Maintenance Manual referenced earlier will likely have about 1/2 way through the 70+/- pages, instructions on how to calibrate the dipstick.

Which go something like this.

Tuesday afternoon drain all the oil from the sump, leave the plug out. Pull the filters.
Wednesday at 10:00 am put xx quarts of oil in the valve cover oil filling port after you put on new filters and installed the plug.

After lunch install and remove the dipstick. That is now the new add level. Check it a few time and mark (a punch or hacksaw) the dipstick with the add mark.
Now add yy quarts of oil and mark the full level. You’re done.

Yeah I’ll look in the manual for the dipstick calibration. Thanks for the information

 

[Mac2]

Yeah I’ll look in the manual for the dipstick calibration. Thanks for the information

Keep us posted on your results and I will do the same.

 

[sunchaser]

A not uncommon happening is that too much old oil remains in the pan. If your dipstick is not accurate and recommended oil volume is added, a serious over fill and oil loss will occur.

Heed David M’s advice about running that engine hard. 5 minutes per day isn’t enough. The 3116 was designed to run at higher RPM thus why it needs to be run hard occasionally when used for hours on end at low RPM

 

[High Wire]

When my friends boat with twin 3116's was commissioned back in 1996, the boat was floated then the required amount of oil added (6.5 gallons each I believe) then the dipsticks were marked. In almost 18 years I've never seen him need to add oil mid-season.

 

[Mac2]

When my friends boat with twin 3116's was commissioned back in 1996, the boat was floated then the required amount of oil added (6.5 gallons each I believe) then the dipsticks were marked. In almost 18 years I've never seen him need to add oil mid-season.

Implying dipstick is not designed for boats. That was my feeling, but nice to know you are confirming this.

 

[mainshiptim]

Implying dipstick is not designed for boats. That was my feeling, but nice to know you are confirming this.

Looks like I have some work to do when I get back to my home port next month. Currently exploring the Trent Severn Waterway. Thanks everyone for your input. Much appreciated.

 

[C lectric]

I am one of the ones that suggest running the oil level 1/2 way between the HIGH and the ADD marks.
My reason was not oil burn but alarms triggering due to the oil being whipped into a froth when the crankshaft whips it and the the oil is sucked up which collapses the bubbles untill it returns to the pan and the bubbles reform which often causes the alarms to sound.
However if the oil level is to high then the oil will be burned also.

And YES I had this happen to me and my boat and the fix was to no longer fill to the full mark but rather to 1/2 between the add and the full markings.

No more low oil pressure alarms for the last 20+ years

 

[mainshiptim]

I am one of the ones that suggest running the oil level 1/2 way between the HIGH and the ADD marks.
My reason was not oil burn but alarms triggering due to the oil being whipped into a froth when the crankshaft whips it and the the oil is sucked up which collapses the bubbles untill it returns to the pan and the bubbles reform which often causes the alarms to sound.
However if the oil level is to high then the oil will be burned also.

And YES I had this happen to me and my boat and the fix was to no longer fill to the full mark but rather to 1/2 between the add and the full markings.

No more low oil pressure alarms for the last 20+ years

Yeah I’m going to experiment with lower dipstick readings to see if the burn rate changes

Thank you for your insight