Why are 12 quarts of oil utilized in a Cummins engine?

[Bater]

I changed the oil on the '91 (garage queen) today, and drained out about ten quarts from that 5. 9 engine. This surprised me, having gotten so used to the '08 (daily driver) "making oil" with its fuel dilution. That 6. 7 is always full when the overhead tells me to change the oil. This contrast made me think of some questions, ones that I don't recall ever seeing a discussion on before.

• For instance, just why does a Cummins engine take 12 quarts of oil?
  
• How much motor oil circulates in the engine and filter during operation, versus that left in the pan?
  
• How does the capacity in quarts tie to the contaminant/fuel dilution carrying capabilities of the oil stock?
  
• Where is the oil pickup tube in the oil pan, and how does it relate to oil level during off road operation, steep angles, etc?
  

All thoughts and information welcome!



Andy

 

[HBarlow]

My '01 spec'd 11 quarts but I always poured in three gallons. My '06 and '08 require three gallons. I believe the commercial truck version of the Cummins ISB6. 7 requires 15 quarts. 12 is probably a compromise for the Ram chassis and available space.

I never even check the oil level on my '08. It doesn't use oil and doesn't have fuel contamination.

 

[jhenderson]

The pick up is within 1/2 inch of the bottom of the sump. More oil= less % of dilution by fuel or other contaminants, lower oil temp, and ample supply incase of emergency or bone headed operators who don't check the level regularly.

 

[ata]

and ample supply incase of emergency or bone headed operators who don't check the level regularly.

OH, You just have to smile when somebody knows what there talking about!

 

[fox]

The more oil in the system the more it can cool in the pan. 40 years ago I could tell by the oil pressure in my car if it needed a quart. It would drop pressure by 5-10 lbs when it was low. I've often said the mopar small block lasted longer because they took 6 with filter vs. the chevy with 5.

 

[Bater]

Good comments already. I hadn't thought about the oil cooling potential of a large sump.



Some online reading shows similar Cummins B series engines, for heavy duty applications, with oil pans with even higher capacities.



"A larger 18-quart oil pan option allows 25% longer oil change intervals. Additional oil in the sump means that the additive package can keep protecting your engine components longer. That translates into an extra 5,000 miles (8,000 km) between oil and oil filter changes. "



So Harvey I bet you are correct, 12 quarts was the original compromise that Cummins engineers struck for what would fit in a light duty truck.



Interesting that the number of quarts has stayed consistent across nearly 25 years of use in Dodge pickups, even though the later engines have much bigger displacements and greater horsepower. I gather that better motor oil has allowed that to be the case.

 

[Mikey-KE7LBB]

I never even check the oil level on my '08.

How do you know this to be true if you don't check it??

It doesn't use oil and doesn't have fuel contamination.

I'm guessing that you sent a sample to a lab to confirm this??

 

[Grizzly]

Powerstroke diesel engines take 14 qts. Perhaps because they burn it too fast!

 

[RonD]

My 6. 7 takes 12 quarts of oil with an oil filter, that is what fills it to the upper line, it has never made oil, I have no detectable fuel in the oil, the oil reminder light has never come on, I currently have 6500 miles on the current oil, it will get changed when I get home from this trip, my guess the oil will have 8-9000 miles on it, yes I use the truck for what it was designed for.

 

[Surefire89]

My 6. 7 takes 12 quarts of oil with an oil filter, that is what fills it to the upper line

Is there a reason why you fill it to the upper line?

I have always been under the understanding that overfilling your engine is equally as bad as underfilling it, due to oil changes that leave some old oil in the engine and that if you were to get some kind of fuel contamintation into your oil you will need room in your pan for it to go. If there is no room for it to go your crank will dip into it, creating air in your oil and a possible an overheating issue or atleast running a bit hotter than it should. Correct me if im wrong, thats just how I grew up.

I like to put 10 quarts in mine and have never had any issues. With proper deletes your oil will be good from anywhere between 7500-10,000.

 

[Surefire89]

How do you know this to be true if you don't check it??

I'm guessing that you sent a sample to a lab to confirm this??

You shouldnt have to check your oil ever if you know what your looking at on your oil pressure gauge. I cant speak for HBarlow but hes a smart dude and I bet would send out a sample to a lab every oil change as I do, considering how cheap they are and how informative they can be.

 

[RonD]

There is a min, and a max on the dip stick, I fill per the book to 12 quarts, my engine will never have diesel in the crankcase, it is used 99% of the time with 14000 pounds connected to the rear, I check it every couple of thousand miles, it never changes up or down, my 2005 5. 9 was the very same.

Is there a reason why you fill it to the upper line?

I have always been under the understanding that overfilling your engine is equally as bad as underfilling it, due to oil changes that leave some old oil in the engine and that if you were to get some kind of fuel contamintation into your oil you will need room in your pan for it to go. If there is no room for it to go your crank will dip into it, creating air in your oil and a possible an overheating issue or atleast running a bit hotter than it should. Correct me if im wrong, thats just how I grew up.

I like to put 10 quarts in mine and have never had any issues. With proper deletes your oil will be good from anywhere between 7500-10,000.

 

[jhenderson]

You're gauge won't show any pressure loss until you drop below the pickup. It's run by the ECM and senses whether the is minimum pressure and sends a signal to the gauge based on rpm and engine temp. It's no more than an idiot light. While some of you took pleasure in my post, I would have used more tact if I had seen Harvey's post before I answered the question. I'm not in the habit of name calling, but this struck a nerve. As a boy, one of my friends from school worked for a local turf farmer. He was told to bring a tractor back to the shop. The key would be in it. He came back and said there was no key. The farmer took him to the tractor, opened the side cover, and there was the key, hanging off the dipstick. He said, ' didn't I tell you to always check the oil?' The farmer already knew what I have learned. Equipment is too expensive to forget the small stuff.

 

[Bater]

Ah, I see now that the way I worded my original post could lead to a belief that I never check the oil in my vehicles. And yet, just today the Mrs. yelled at me for adding half a quart of oil to her Jeep CRD when I was supposed to be washing walls prior to painting.



Anyhow, what I was attempting to relate (and I think Harvey too), is that with the 6. 7 I have never had to add oil between changes. Dipstick always comes back full, so you do become complacent. My Deere dozer is the same way, doesn't use a drop. Case IH farm tractor a little bit so many hours, etc. You get a feel for each machine and check the level at requisite intervals. But admittedly yes, I probably should check more often than that for good measure.



After putting 500 highway miles on the '91, a rarity, I was indeed surprised that I drained out 10 and put in 11 quarts to get that rig back to the full mark. That got me thinking about just how much oil these engines really required and why, and in particular, how much oil was needed to keep the pick up tube covered when the truck is at the crazy angles (20 to 25 degrees) that occur on our farm.

 

[Tractorat]

Is there a reason why you fill it to the upper line?
The upper line is ideally where the level should be. You are OK if it is between the upper and the lower. But if it goes below the lower, you need to add oil to at least the min.

BTW, my truck is an 02. The manual says 10 in the engine and 1 in the filter. That always brings it right to the full line.

 

[seafish]

As a boy, one of my friends from school worked for a local turf farmer. He was told to bring a tractor back to the shop. The key would be in it. He came back and said there was no key. The farmer took him to the tractor, opened the side cover, and there was the key, hanging off the dipstick. He said, ' didn't I tell you to always check the oil?' The farmer already knew what I have learned. Equipment is too expensive to forget the small stuff.

GREAT story!!!

 

[BK]

interesting question... how much stays in the pan vs circulating on the engine.....

My 99 , per the manual , and it goes just right about the fill line. .
10 on the pan, and 1qt in the filter.

My oil pan, the sump part of it, don't see how they can make it much bigger. And for the part that's above the cross member, don't see how that could be any deeper.
So I've always guessed the capacity being lower in the 99's Dodges (vs newer model years vs heavier duty applications) were due to what they could really fit in there for a pan.

So if the block is the same, and other other heavy duty applications of the 5. 9B have larger capacities, I guess the pan is larger and or also secondary cooling for the oil = more oil capacity ?
And yea, interesting, how much of the oil is really moving around the block/filling the block once the pump is going ???

 

[WalterJ]

2-4 Qts. flyin' 'round

My racing friends have experienced 2-4 quarts in 'circulation' during 'highway' speeds, in a gas engine.