Black streaks in clean oil

[Chris B.]

So I was curious if this is normal? I always change my 2004 Volvo XC70 with Mobile 1 0w40 every 5,000 miles its entire life of 165,000 miles. Last oil change I stuck my finger in the drain hole and when I pulled it out I noticed black carbon specks and streaks in the clean oil on my finger. I always dump a quarter quart of clean oil as a flush and let it drain for a couple hours so this is right after that. I was surprised to see this black stuff. Maybe it settles on the bottom of the oil pan? Anything to worry about? Here is a picture:

 

[OM605]

Nothing to worry about. As you said, tiny carbon particles always settle at the bottom of the pan. It used to bother me as well when changing the oil on my car that had 10k OCI since new but after a few 3 or 5k OCI it was a lot less visible but still present and i notice it on every gas car that has a properly designed drain hole.

 

[demarpaint]

If it really bothers you, you could try pouring about half a quart or so of clean oil into the engine with the drain plug out after draining the oil to carry some of the particles away. It might help, some may consider it wasteful, I won't comment either way. In all honesty I don't think you have anything to worry about.

 

[AKhan87]

I always change my 2004 Volvo XC70 with Mobile 1 0w40 every 5,000 miles its entire life of 165,000 miles.

nice! does it burn oil between oil changes? and is it the 2.5L NA version?

I drove a 2004 Volvo s60 from 160k to 195k, it used to burn 1 qt in 1000 miles, after I started to use Mobil 1 0w40 it went to 1 qt in 1500-1600 miles, so I thought that was nice.

Last oil change I stuck my finger in the drain hole and when I pulled it out I noticed black carbon specks and streaks in the clean oil on my finger.

absolutely nothing to worry about, and yes it can settle at the bottom of the pan, during my time of rebuilding engines, that would show up in 30k miles after the rebuild, even after using full synthetic motor oils, that is nothing of concern as long as your engine doesn't have any issues that your aware of

I always dump a quarter quart of clean oil as a flush and let it drain for a couple hours so this is right after that.

that's a total waste of oil, and I have no idea what your accomplishing by doing that, your not flushing anything really, feels like you're just doing something to make yourself feel good because you did something that is considered "cheap insurance" maybe?

 

[Chris B.]

nice! does it burn oil between oil changes? and is it the 2.5L NA version?

I drove a 2004 Volvo s60 from 160k to 195k, it used to burn 1 qt in 1000 miles, after I started to use Mobil 1 0w40 it went to 1 qt in 1500-1600 miles, so I thought that was nice.


absolutely nothing to worry about, and yes it can settle at the bottom of the pan, during my time of rebuilding engines, that would show up in 30k miles after the rebuild, even after using full synthetic motor oils, that is nothing of concern as long as your engine doesn't have any issues that your aware of



that's a total waste of oil, and I have no idea what your accomplishing by doing that, your not flushing anything really, feels like you're just doing something to make yourself feel good because you did something that is considered "cheap insurance" maybe?

It is the 2.5 Turbo. It burns little oil over the 5,000 mile OCI, like 8 ounces total to keep it right at the full line on the dip stick. Runs like its brand new! Yeah I was just trying to flush out more old oil. Do it with all my engine.

 

[Krieg]

TBH it doesn't look clean!

 

[Chris B.]

Thanks gentlemen!

 

[CharlesInCharge]

So I was curious if this is normal? I always change my 2004 Volvo XC70 with Mobile 1 0w40 every 5,000 miles its entire life of 165,000 miles. Last oil change I stuck my finger in the drain hole and when I pulled it out I noticed black carbon specks and streaks in the clean oil on my finger. I always dump a quarter quart of clean oil as a flush and let it drain for a couple hours so this is right after that. I was surprised to see this black stuff. Maybe it settles on the bottom of the oil pan? Anything to worry about? Here is a picture:

If I understand correctly, you drain the oil, then pour 1/4 qt of clean oil right down and thru it and that drains out.

Then no, the oil coming out is no longer "new" it's probably doing exactly what you had intended, flushing out small amounts of gunk. So it goes from clean to dirty instantly. I would expect the clean oil to come out dirty as your picture shows.

I'm not sure what you are hoping to accomplish. You're really just wasting your time and clean oil. When you do an oil change, no matter how long you drain it, around 5-15% of oil remains in the engine block, so you are never truly getting out all the oil with a typical drain and fill.

If you really wanted to dillute that remaining 5-15%, what you should do is drain the pan, install the plug, do a oil fill, run the car on a very short OCI either just idle it or run it a few days, and then drain that. That would maybe be able to get out most of the oil dirty oil. But I think this is typically OC behavior and overkill.

 

[R1jake]

If it really bothers you, you could try pouring about half a quart or so of clean oil into the engine with the drain plug out after draining the oil to carry some of the particles away. It might help, some may consider it wasteful, I won't comment either way. In all honesty I don't think you have anything to worry about.

You must not have read his post.

 

[demarpaint]

You must not have read his post.

Interesting comment, do you know what I'm thinking? lol FTR I read his post and felt he had nothing to worry about.

 

[AKhan87]

If I understand correctly, you drain the oil, then pour 1/4 qt of clean oil right down and thru it and that drains out.

Then no, the oil coming out is no longer "new" it's probably doing exactly what you had intended, flushing out small amounts of gunk. So it goes from clean to dirty instantly. I would expect the clean oil to come out dirty as your picture shows.

I'm not sure what you are hoping to accomplish. You're really just wasting your time and clean oil. When you do an oil change, no matter how long you drain it, around 5-15% of oil remains in the engine block, so you are never truly getting out all the oil with a typical drain and fill.

If you really wanted to dillute that remaining 5-15%, what you should do is drain the pan, install the plug, do a oil fill, run the car on a very short OCI either just idle it or run it a few days, and then drain that. That would maybe be able to get out most of the oil dirty oil. But I think this is typically OC behavior and overkill.

exactly, I have rebuilt many engines, and there is always about half a quart still left between the bearings and the crankshaft housing, without running the oil pump, your not going to get out that left over oil by simply pouring through clean oil, just because your pushing out settlements at the bottom of the oil pan by maybe 1%, it isn't the same as dropping the oil pan and cleaning it thoroughly, its literally a waste of oil to do that...

 

[Chris B.]

Appreciate it again, everyone! Sounds like nothing to worry about.

 

[930.engineering]

Black streaks in clean oil​

Last oil change I stuck my finger in the drain hole and when I pulled it out I noticed black carbon specks and streaks in the clean oil on my finger. ....

If there are black streaks it isn't clean oil to begin with. It's normal that about 15 - 20 % of the old oil is remaining in the pan, the cylinder head and elsewhere (IMHO "5-15%" is an unrealistic estimation). You could reduce the dilution of the fresh oil with old if you screw the drain plug in and fill two or three quarts of fresh oil in, then drain it. You won't get it out entirely though.
.

 

[CharlesInCharge]

If there are black streaks it isn't clean oil to begin with. It's normal that about 15 - 20 % of the old oil is remaining in the pan, the cylinder head and elsewhere (IMHO "5-15%" is an unrealistic estimation). You could reduce the dilution of the fresh oil with old if you screw the drain plug in and fill two or three quarts of fresh oil in, then drain it. You won't get it out entirely though.
.

So rather than about 1/4 to 1/2 a quart, which you say is "unrealistic," in the average car engine with a 5 qt fill, you think there's typically a full quart extra in the engine? Is a factory fill of 5qt engine actually 6 qts, plus the filter, as you suggest? That's pretty sizeable wouldn't you say?

 

[BHopkins]

So rather than about 1/4 to 1/2 a quart, which you say is "unrealistic," in the average car engine with a 5 qt fill, you think there's typically a full quart extra in the engine? Is a factory fill of 5qt engine actually 6 qts, plus the filter, as you suggest? That's pretty sizeable wouldn't you say?

One of the biggest misconceptions of oil change do-it yourself types is that it is possible to drain 100% of the old motor oil, just by giving it time to all drain out. It never happens.

Every engine retains somewhere between 1/2 quart to almost 2 quarts at oil change. (The SL550 I used to drive takes 9 quarts at oil change, but has a total capacity of 10.8 quarts.) It is not unusual for service manuals to show two values for motor oil capacity - one for oil and filter change and one for total capacity for engine rebuild. This extra oil stays in places like the passages between the oil pump and the oil filter.

I used to be one of those also that would leave the drain plug out for an extended time, and go find something else to do while every last drip drained. Or so I thought. Once I learned that this never happens, it has changed my practice. Now, once the oil stream goes from a stream to a drip, it's time to put put the plug in and fill the engine with fresh oil.

OP, BTW, great job on being disciplined on oil changes for the lifetime of the car. I'm also a big fan of M1 0W-40.

 

[CharlesInCharge]

One of the biggest misconceptions of oil change do-it yourself types is that it is possible to drain 100% of the old motor oil, just by giving it time to all drain out. It never happens.

Every engine retains somewhere between 1/2 quart to almost 2 quarts at oil change. (The SL550 I used to drive takes 9 quarts at oil change, but has a total capacity of 10.8 quarts.) It is not unusual for service manuals to show two values for motor oil capacity - one for oil and filter change and one for total capacity for engine rebuild. This extra oil stays in places like the passages between the oil pump and the oil filter.

I used to be one of those also that would leave the drain plug out for an extended time, and go find something else to do while every last drip drained. Or so I thought. Once I learned that this never happens, it has changed my practice. Now, once the oil stream goes from a stream to a drip, it's time to put put the plug in and fill the engine with fresh oil.

OP, BTW, great job on being disciplined on oil changes for the lifetime of the car. I'm also a big fan of M1 0W-40.

I have not disagreed with that concept. But I would need to see some evidence that TWENTY percent is still in the engine with the filter removed. That seems like a lot.

 

[930.engineering]

Evidence has been given a hundred times on this forum. You should read the forum instead of
starting new topics every day. Nothing wrong with starting a new one if you have a completely
new question, however please don't expect it never has been discussed before without even
doing a search. Prepare to be surprised - reading some older discussions is most probably more
interesting than debating the horrendous cost of auto-dimming rearview mirrors. Take this as
an honest advice please.
My GTI's 2.0 engine has a total oil capacity of 6.6 liters, while oil change requires just 5.7 liters.
So it still keeps almost one liter/quart (!!!!). While I have no specific number on hand it isn't that
much less on my Mini's engine. Barely a surprise at all when you see the oil pan with its reversely
recessed drain plug hole. Oil change requires just 4.0 liters, a tiny bit above 4 quarts. I'd bet it's
half a liter remaining at least, perhaps 0.7 l - even on this tiny engine.

The drain plug isn't the deepest point and that's just the oil pan.
.

 

[BHopkins]

I have not disagreed with that concept. But I would need to see some evidence that TWENTY percent is still in the engine with the filter removed. That seems like a lot.

Although there may be some, I'm not aware of any engines that retain 20%. But 15% is absolutely not uncommon.

From the factory service manual for my wife's Outback with the FB25 engine, total capacity at overhaul is 6.0 quarts. Filling amount when replacing oil and filter is 5.1 quarts. That calculates to 15% retained. For the Subaru 3.6 engine, total capacity is 8.2 quarts. Oil and filter change is 6.9 quarts for just under 16% retained. The numbers I quoted above for my old SL550 are from memory, and I may be off by a couple tenth's one way or the other, but you can see that it is about 17%.

With this knowledge, it helps understand why motor oil can look dirty almost immediately after an oil change. It is not that the engine is already making the oil dirty, but that the fresh oil has already been mixed with old oil.

 

[Chris B.]

One of the biggest misconceptions of oil change do-it yourself types is that it is possible to drain 100% of the old motor oil, just by giving it time to all drain out. It never happens.

Every engine retains somewhere between 1/2 quart to almost 2 quarts at oil change. (The SL550 I used to drive takes 9 quarts at oil change, but has a total capacity of 10.8 quarts.) It is not unusual for service manuals to show two values for motor oil capacity - one for oil and filter change and one for total capacity for engine rebuild. This extra oil stays in places like the passages between the oil pump and the oil filter.

I used to be one of those also that would leave the drain plug out for an extended time, and go find something else to do while every last drip drained. Or so I thought. Once I learned that this never happens, it has changed my practice. Now, once the oil stream goes from a stream to a drip, it's time to put put the plug in and fill the engine with fresh oil.

OP, BTW, great job on being disciplined on oil changes for the lifetime of the car. I'm also a big fan of M1 0W-40.

Thanks haha! I maintain 3 vehicles and all of them have NEVER seen an oil change that I have not done myself. Just dont trust anyone including the dealer.

 

[CharlesInCharge]

Evidence has been given a hundred times on this forum. You should read the forum instead of
starting new topics every day. Nothing wrong with starting a new one if you have a completely
new question, however please don't expect it never has been discussed before without even
doing a search. Prepare to be surprised - reading some older discussions is most probably more
interesting than debating the horrendous cost of auto-dimming rearview mirrors. Take this as
an honest advice please.
My GTI's 2.0 engine has a total oil capacity of 6.6 liters, while oil change requires just 5.7 liters.
So it still keeps almost one liter/quart (!!!!). While I have no specific number on hand it isn't that
much less on my Mini's engine. Barely a surprise at all when you see the oil pan with its reversely
recessed drain plug hole. Oil change requires just 4.0 liters, a tiny bit above 4 quarts. I'd bet it's
half a liter remaining at least, perhaps 0.7 l - even on this tiny engine.

The drain plug isn't the deepest point and that's just the oil pan.
.

Thank you. You're overexplaining the obvious concept that I think we all get, but your estimates are wildly high unless you have others to bring forward.

Your example of 5.7 of 6.6 is 8% remaining. Not 15% to 20% as you stated. It's squarely in the 5% to 15% I stated.

Further, the oil filter hold some, maybe 25% of 1 qt. My manuals generally provide a fill suggestion of 1/4 to 1/2 difference with or without the filter (less without a filter change, more with a filter change). This brings the number lower, if we are just talking about the amount remaining IN THE ENGINE areas, not counting filter. So I'll repeat, somewhere in the 5 to 15% range is contained in the engine and your example is 8%.

Do you have common examples exceeding the high end of my estimate, 15% and into 20% per your statement?