First off, thanks for everybody that helped me figure out my engine temp issue.

So I got the chance to get out of town for a couple days and took a little road trip to visit some friends. After 3 hours of freeway speeds I pulled into town and let off the gas and the oil pressure dropped WAY lower than normal so I immediately pulled over and opened the hood and sure enough it was low on oil. It was good when I left on the trip and it doesn't seem to burn oil driving around town. After 3 hours on the freeway it had burned 3 quarts of oil

What would cause it to burn so much at freeway speeds but not around town?

Model and Year of your car?

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Sam

84 300SD 350K+ miles ( Blue Belle )

Higher blowby at high rpms.Or need better blow by oil seperator.Check turbo for oil.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt

What type of oil are you running? synthetic? dino? 10/40? 5/40? Model? Year?

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If it's a 240D, I believe they naturally burn oil above 80 MPH.

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"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes

1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod

2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die."

Smoke?
Mileage on Engine?
What does the what is coming out of the Tail Pipe smell like?

External leaks will leak more under a higher sustained Crankcase Pressure.

Some of our Members have had the littl O-ring go bad in the Fuel Supply/lift Pump and have claimed that it sucks Oil into the Fuel Supply/Lift Pump and that Oil gets mixed with the Fuel and burned in the Engine.

It is hard to tell if the Compressor side of the Turbo is leaking Oil because if you have a lot of Blow-by that can get everthing coated with Oil as well as the Intake Manifold.
If there is a pool of Oil in the bottom of the Turbo Compressor Housing suspect the Turbo seal on that end.

On the exhaust side of the Turbo you should see dry Carbon buildup. If there is Oil leaking into there the Carbon will be shiny and wet looking. Oil there usually causes some smoke and the exhaust to smell bad.

To determing if it is the Turbo of coming out of the Engine you need to remove the Turbo and look at the Exhaust Ports in the Head. If the Exhaust Ports in the Head have that wet shiny Carbont then the Oil is coming from the Engine or going thourh the Intake and through the Engine.

If the Valves have a lot of Carbon Build up on them it could be the Valve Stem Seals or the Valve Stem to guide clearance is no good.

If you pull the Injectors and look down into the Pre-combustion Chambers you sould also see a light coat of dry Carbon. IF it is thicker and shiny and wet looking you are burning Oil on that cylinder.

On Gasoiline Engines during overheating I have read of the Cylinder Walls getting glazed. That means extremely smooth. When that happens the Piston Rings will not seal as well against the Cylinder Walls.

If the Cylinder Head warped near an Oil Passage it is possible for Oil to leak into a near by Cylinder.

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84 300D, 82 Volvo 244Gl Diesel

Yes, but not that much. I drove mine from Carson City, NV to Atlanta and back, pretty much floored the whole time and only burned a couple quarts.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

You have not identified the car model. So my answer is incomplete.

It sounds to me like there is a good possibility you just burnt water condensate off in the oil. If the return trip does not exhibit the same consumption you have your answer.

Condensate builds up in engines on short in town trips that does not get burnt off. The base oil does not get hot enough to turn it to steam and leave the engine.

Out on the highway running at speed burns it off. It is not healthy for an engine too have too much condensate present. A periodic run to burn it off if it turns out to be the reason and that will be proven on your way back. One way or another.

If so one has to do the occasional run or change oil more often. Cold weather increases the condensate growth faster. .

Piston speed is quite a bit higher on the 240d. Because of the higher highway rpms that are otherwise much lower on the five cylinder 300d.

For a given speed that is. The five cylinder I suspect would act the same if the higher ratio rear end of the 240d where installed in one.

Above a certain piston speed the oil rings do not seem to wipe the walls down well. Or as well as some designs. This may actually make the engine wear less over time so is not all bad. To me in fact this is normal on these engines. Because of the higher thrust side loads on the pistons and walls of a diesel. There is a chance this was a purposeful design feature of the engine. I never owned a brand new one so cannot really compare to verify what I have suspected.

Just to be clear, I was describing the oil consumption of my 240D.

I made a similar trip in my 300D, but I changed the oil in Atlanta, then made a side trip to Miami and then back to Atlanta before heading home. I don't recall the car using any oil on that trip.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

fairly recently purchased a 81 300D NA sedan for a screamin' deal

With no window switches and ran hot on inclines.

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Greg
2012 S350 BlueTEC 4Matic
2007 ML 320 CDI
2007 Leisure Travel Serenity
2006 Sprinter 432k
2005 E320 CDI
1998 SLK230 (teal)
1998 SLK230 (silver)
1996 E300D 99k, 30k on WVO
Previous:
1983 240D, on WVO
1982 300D, on WVO
1983 300CD, on WVO
1986 300SDL 237k, 25k on WVO (Deerslayer)
1991 350SDL 249k, 56k on WVO - Retired to a car spa in Phoenix
1983 380 SEC w/603 diesel, 8k on WVO
1996 E300D 351k, 177k on WVO

Engine Milage?
If no external Oil Leaks I would suspect worn Valve Stem Seals and or Guides.
Replacing the Valve Stem Seals is not hard but time consuming. The parts are cheap.
Of course if the Valve Stems and Guides are worn nothing can be done about that without major work.

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84 300D, 82 Volvo 244Gl Diesel

Some vehicles will burn a bit of oil by way of the oil/vapor separator being overwhelmed at high rpm, but three quarts in three hours is A LOT. Are you sure the oil was full when you left for your trip? Have you found any signs of external leaks?

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

Most likely, you checked the oil before starting the engine when you were about to leave.... then, checked the oil immediately after shut down.


Check the oil within 5 minutes of shutdown.

There is a very large discrepancy between oil levels depending on how / when you check it.

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Sorry, I completely spaced on mentioning what engine it is, it's an 81 300D NA. I got it dirt cheap, but like GregMN said it seems to present a new problem as fast as I can fix the last problem. The return trip did not burn any oil so I'm thinking it was probably water in the oil, which wouldn't surprise me since the PO didn't seem to do any other maintenance on the car.