Freshly changed oil in a Diesel engine black?

[NavyVet88]

Age old question and expected responses.

Just curious as to why exactly a fresh oil change in a Diesel engine may or may not bring about an immediate black oiled dipstick?

I've read threads here previously where one person would ask the question and some responses would say yes and some say no.

 

[440Magnum]

It doesn't take much time for a diesel engine to put enough soot in the oil to show black on the dipstick within a few hours of operation. Period- engine type doesn't matter much.

Now whether or not the oil turns INSTANTLY dark after a change and first start depends on other things... mainly how much old soot-loaded oil remains in the engine during a routine drain/fill type oil change. On things like a Navistar T444 (Powerstroke 7.2) there's a pretty large volume of oil (a quart or more) in the HPOP system that doesn't get changed unless extra steps are taken, and quickly mixes with the new oil, turning it dark. Even in engines without a "hidden" oil volume like that, designs that have larger pooling places in the heads and intake valley will turn the change dark even quicker.

 

[bullwinkle]

Depends on the amount of soot in the residual oil & crankcase. Also, some diesels make more (bad injectors, CR multiple injection events, etc.).

 

[Koz1]

Its called EGR, Get rid of it.

 

[UncleDave]

Diesels typically blacken right away - pretty normal.

I have a bunch of them and they all exhibit that trait as do all my friends diesels.


UD

 

[JMJNet]

As said by UncleDave.

The member who answer "no" are those who never own a diesel vehicle.

Yes, it should go black that means the oil is working to float the soot. Soot is smaller than the oil filter can filter so it will keep floating in the oil.

Generally, the engine oil in a diesel needs to be changed more often although the oil and filtering technology have been able to make the oil last longer despite the fact that it goes black almost instantaneously.

Used Oil Analysis needs to be done for extension of Oil Change interval.

 

[UltrafanUK]

Originally Posted By: Koz1
Its called EGR, Get rid of it.


Don't get rid of an EGR as NOx is nasty stuff. If you delete an EGR the engine will take longer to warm up which increases in cylinder deposits and they don't cause an increase in engine wear. They don't turn the oil black!

New diesel oil will turn black if the engine was designed in such a way that it has a significant amount of residual oil. Obviously if that oil was well used, it will turn the new oil black fairly quickly.

If my diesel oil turns black too quickly after an oil change, I just run an idle flush just before the next OCI, but try and avoid using any type of flush additive if you already have an oil leak issue, as it will increase the drip rate for a while due to the false oil seal effect.

 

[Lyman]

Been driving diesels since 1981. It's normal!

 

[Chris142]

Mine turns black before I even start it.its normal. It does not have an egr

 

[Chris142]

Originally Posted By: Koz1
Its called EGR, Get rid of it.
diesels were turning oil black decades before they started putting an egr on them

 

[austinlunsford]

My 7.3 Powerstroke turns the oil black within a couple hundred miles. And I always change the oil in the high pressure oil pump reservoir too.

 

[abycat]

my 6.0 has no egr and isn't stock but it takes a bit for the oil to get black. It still always has a hint of brown in it so I don't think I get as much soot in it as others. my stock oil cooler is still in so I only have about 1 quart I can't get to when I do a change. It will be about 2 when I install a custom oil cooler. which still doesn't matter. On a 6.0 you would have to spend hours removing the top of the engine to get to the reservoir, plus 100$ in gaskets and orings every time.
Really the two things that determine soot in oil levels are emissions and what condition the engine is in.

 

[A_Harman]

I had the oil changed in my Cummins Dodge 2 months, 2000 miles ago, and it has still only reached a medium gray color. Not every engine is the same due to differences in fuel injection systems. But EGR engines have been known from the start as being particularly bad for sooting the oil. That is why the CI4+ oil specification was rushed into production so quickly after EGR engines were introduced in 2006.

 

[totegoat]

The oil in my 5.9 Cummins looked clean for a few miles. 6.7 turns black almost immediately due to the smog equipment. Old CAT and Detroit engines were black quickly.

 

[Koz1]

Its the EGR if its instantly black.
If you dont have EGR then you run rich or have a ring issue.

 

[OneEyeJack]

If you want to remove more soot you need something like a toilet paper oil filter.

 

[Trav]

Fill the oil, start it, check the level and its black. Its totally normal.
Its not EGR, bad injectors or anything eles wrong with it, its in the DNA of the oil burner.

 

[Trav]

Originally Posted By: Koz1
Its the EGR if its instantly black.
If you dont have EGR then you run rich or have a ring issue.


That's not true. The older non egr MB diesels were black so fast you thought you black oil in them. They were relatively new low Km engines and did that, those engines had a million Km in them with ease.

 

[userfriendly]

UOAs on my DPF equipped LML Dmax show very low soot loading compared to the samples from heavy trucks.

Would the engine last longer with a fancy bi-pass filter?

 

[JHZR2]

Originally Posted By: Koz1
Its called EGR, Get rid of it.


No it's not. It takes only a tiny bit of carbon black to act like ink and blacken the whole load of oil. The remnant oil in the sump is enough.