Using Some Oil

[Roy W]

Since new, my '05 LLY has used oil when on extended trips pulling my 9K travel trailer. Not a lot, but maybe a quart in 1500 miles. When not towing, oil consumption was zero. Recently however, (with 107K) it's started using oil when not pulling the trailer. I just checked it and it's just touching the end of the dipstick with 4000 miles on the oil change. (2 quarts low ?) There is zero evidence of any leaks or drips.(new concrete driveway). The pvc system was eliminated about 30K ago and the egr is blocked.The valve covers are vented to the atmosphere and you can't even get a drop on a tissue on the end of the hoses. No oil smoke under any conditions. I started out using Delo 400 and about 3 oil changes ago switched to Mobil Delvac, with no change in oil useage. I change oil and filter every 5000 miles, fuel filter every 10,000 miles.

I'm not in panic mode, but searching for ideas as to what would be causing the oil useage.

[DmaxMaverick]

How much oil are you filling at change?

We are not discussing a gasser. Oil burning in a Diesel combustion chamber is almost always undetectable. If you get enough oil in the cylinder(s) to show significant smoke, the engine won't shut off until the oil supply stops. Engine oil, to the engine, is no different than fuel oil. They are one in the same, once in the combustion chamber. At most, you may notice an odor at the tailpipe, which is the additive package burning off, which is formulated to resist burning.

That said, 1 qt. over 1-2,000 miles is not necessarily significant, and well within what GM considers "normal", under the conditions you are describing. They calculate oil consumption according to quantity of fuel burned at the same time, which should be significantly greater while towing 9K. They would also not consider using 2 qts. at 4K miles worthy of their time, unless you have an external leak.

If you have a minor usage, and it's going through the combustion process, I wouldn't worry about it. I suggest watching the quantity, and don't be concerned unless it increases under the same conditions.

Also......
I don't normally recommend Rotella T, but try some (for testing). In nearly every vehicle I've seen use it, it always went away at a greater rate than the other popular brands (about double the rate). Watch the oil level for a different trend than what you've seen thus far. Theoretically, it should use more, which may help you find the source. It also has a more pungent odor when burned, which may also be helpful. Or, perhaps, your truck is backwards, and it won't use any at all. YMMV

[Kennedy]

You did not specify Delvac 1 or 1300

Switch to Mobil Delvac 1 5w40 and you should see a minimum 50% reduction from what I have seen. I've never made the change myself as I run this oil pretty much universally.

IMHO the PCV reroute is going the wrong way. I want to have an active scavenge pulling the vapors (moisture) from the crankcase. These vapors are what condense and create acids in your oil.

[Roy W]

Thanks for the insight to my oil consumption issue. The oil quantity at change is 10 quarts (2 gallons and 2 quarts) and I've been using the Delvac 1300. Because I'm 2 quarts low now at 4K, I'll go ahead and change it, and try the Delvac 1. My rationale for the pvc reroute was to eliminate the possibility of crankcase pressure pushing oil past the rings, but based on no evidence of oil at the breather hoses I guess that's not an issue........ We'll see what the next 5000 mile change brings.

[DmaxMaverick]

The concept of PCV is just the opposite. If the system is operating properly, it should maintain a constant slight vacuum on the crankcase, eliminating the possibility of "pushing" oil past the rings. There's nothing wrong with PCV, other than an oily intake, turbo, plumbing, and CAC.

If you were concerned that oil was passing the rings and being burned, you eliminated the defense against that by removing the PCV. Your usage is coming from somewhere else, and it isn't the valve guides, either (can't/won't happen in any noticeable amount).

[Roy W]

DMax,

I had reason to believe that the vacuum source for the OEM pcv system (turbo intake) was minimal. Prior to doing the pcv reroute I had "oil rings" around every intercooler hose connection. Following the re-route and an engine degreasing, after 30K miles, there is no evidence of even the slightest oil ring around the intercooler connections. That led me to the conclusion that there was oil vapor circulating under turbo pressure through the intake system, leading to air flow inefficiency and potential future problems with liquid oil settling out in the intercooler. With the pcv re-route, I somewhat expected to see evidence of oil vapor condensing and dripping from the breather hoses however that has never occured. This modification was all done as a procedural step in reducing oil consumption. Maybe the real problem is a slight oil seal leak in the turbo. Is the fact there is evidence of "oil creep" at the ERG block off plate telling me something ??

[Kennedy]

Switch to Delvac 1 and report back what you find. I believe that what you are experienceing is more of a volatility burn off.

Also, what are you using for air filter?

DMax,

I had reason to believe that the vacuum source for the OEM pcv system (turbo intake) was minimal. Prior to doing the pcv reroute I had "oil rings" around every intercooler hose connection. Following the re-route and an engine degreasing, after 30K miles, there is no evidence of even the slightest oil ring around the intercooler connections. That led me to the conclusion that there was oil vapor circulating under turbo pressure through the intake system, leading to air flow inefficiency and potential future problems with liquid oil settling out in the intercooler. With the pcv re-route, I somewhat expected to see evidence of oil vapor condensing and dripping from the breather hoses however that has never occured. This modification was all done as a procedural step in reducing oil consumption. Maybe the real problem is a slight oil seal leak in the turbo. Is the fact there is evidence of "oil creep" at the ERG block off plate telling me something ??

The PCV system will draw out oil vapors and moisture. This can condense and make a bit of weep, but the actual amount of oil passing through is negligible as you have come to realize. That little bit of oil in the intercooler is really no big deal so long as it is not allowed to meet with EGR soot with which it will combine to make a tar like substance.

A slight oil seal leak in the turbo would produce the same "oil ring" evidence that you describe. By doing the PCV reroute you eliminated the prime source of oil (albeit quite small) in the intake tract.

[Roy W]

John,

I haven't been able to locate any Delvac 1 locally. Mostly, Rotella, Delo, and Delvac 1300. What is the difference between Delvac 1 and Mobile Turbo Diesel Truck. They are both 100% synthetic.

I use a Fram Heavy Duty air filter and a Purolator Pure One ($17.00) oil filter.

[Kennedy]

The Mobil TDD is same as D1. Give it a shot and see what it does. I just had a customer report a 50% reduction in consumption after switching his LMM. I'm surprised Mark Rinker hasn't seen this one. Must be busy plowing snow.

FWIW I've never been a fan of anything that Fram makes and we have the Baldwin oil filters for about 1/2 what you are paying for the Purolator.

[Mark Rinker]

What John already said. (No snowplowing, still hauling boats in January!)

Delvac stays in my Duramaxes that tow every day all day. This is the flavor I favor. ...but I have never had consumption problems.

[Kennedy]

(No snowplowing, still hauling boats in January!)

I figured as much. Not much plowing going on around here either. Taking advantage of the light snow cover here. Been out in the woods dragging firewood logs on what little snow we do have.