Oil turns dark fast!
 

I just did an oil change in my 1985 300TD Wagon and I noticed that the oil turns dark within a few miles of driving. The technician assured me that in diesel engines the occurence is normal and he sees it all the time. He suggested the engine flush liquid which apparently cleans junk in the engine (done when the old oil is drained and before new oil is poured in). Please tell me that he is right. What would cause this to happen? I thought that oil changes color over time but in my 260E W124 that happens over 4000-5000 miles from the oil change and the oil still remains lighter color then.

P.S. It was -10 this morning with -30 wind chill and after two glow cycles and not being pluged in she started on me the first try!!!

Igor Zeljic, Minneapolis.

That is completely normal... and usual.... there have been some other threads discussing this lately....might do a seach for more peace of mind.....:D

Try this one...

http://www.peachparts.com/shopforum/diesel-discussion/58379-black-oil.html?highlight=black+oil

The seach feature is really useful..... :D

It's the soot generated by a diesel engine, and it's perfectly normal. Change the oil every 3,000 miles, regardless of color, and it will be fine. :D

Mike

Welcome to the world of owning a diesel.

:)

Is the soot a direct result of the sulphur content within the fuel that causes the soot? Because the oil in gassers also becomes dark over time, but is that due totally different circumstances?

Oh yes, change the oil every 3,000 miles or use synthetic oil and change it and filter every 10,000 miles.

Even the MB manuals don't recommend changing the oil every 3,000 miles. That's old wives (or old mechanics) tales.

P E H

PEH, OK, so why did you not tell us how often you recommend changing Dino Oil and filter ?

when i worked in the engine room on a ship the engineers (europeans) changed the oil on the volvo diesel generators every week !

they changed it hot and often!

oh, and those volvo's never ever broke down.

i change every 3mos or 3000 miles whichever comes first.
in the winter i might even change every 2500miles.
i am using dino oil though.

I think the 3000 mile change is cheap insurance... and certainly does not hurt anything ,,, except PEH's sensibilities.... :D

Generally, I think I would avoid the engine oil flush fluids. The ones I have seen consist mostly of kerosene.

If you happen to have what you think is a dirty engine, just start a regimen of changing the oil regularly. Good engine oil has a detergent in it and will slowly work to clean out the most important parts of your engine.

Just my opinion.

Ken300D

Igor,

I started using Mobil Delvac 1 about a year ago, and when I change oil now, at a 6,000 mile interval for all my cars, I can go about 150 miles in my newer Diesel before the oil turns black. I can go about 25 miles in the 240D (maybe longer, but I generally turn the car over to my daughter after a service and see it when it needs another, and by that time the oil is black again). This gives some added confidence the oil is doing a good job cleaning all the old gunk out and adding to engine life.

On my first experience with the 220D in 1972, I changed the oil twice in the basement of the student Union at college, then called the dealer to ask what is up. So don't feel alone in your astonishment of how quick and how black the oil gets. Good luck, Jim

Leather,

It all depends on how the engine is used. If the engine is run until it gets hot almost every time it is started, 5000 miles will be sufficient for Dino oil.

If the engine is used where it rarely gets hot, then it should be changed by length of time not miles. So every 3 months will be OK.

For Synthetic, oil the above can be doubled.

But a flat "every 3000 miles" is ridiculous with no account of how the engine is used or what type of oil is used.

P E H

LOGIC TREE FAILURE ANALYSIS
 

Ok,,, here is my way of considering this oil interval change question....

Is there an engine penalty for waiting too long to change ?

YES.....

Is there an engine penalty if you change "too early" ?

NO

So it is your choice which side of potential error you choose.

You choose the error, you choose the penalty.....

:D :eek:

OK I am going to jump in on this. Everybody, check your owner's manual. Mine says to change the oil every 5K. Now, as everyone knows this is for "normal" driving conditions, not "severe" conditions. Generally speaking, the stop and go driving we do would fall under "severe" driving conditions, in which case the owner's manual says to change the oil every 2500. So with all that said, 3-4K would be a happy medium. Now, as it has been mentioned, using synthetic changes these numbers, but by how much? Has anyone here seen on any oil company's websites, a conversion chart of sorts, mentioning how long one can go between oil changes using syn. versus dino oil? I am not an oil engineer, so I can't say for sure, but I know my owner's manual says to change the oil between 2500-5000 miles depending on the conditions you drive in.

Well, Rick, What took you so long to get lured into this debate.. we have been working on baiting you for days.... I still say fresh oil is cheap insurance against possibly misinterpreting what " severe" service is... which you are correct about many people's situation being that without them realizing it....