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Is this normal for diesels? I have not has one before. This van shows about 12k miles 'till next service due. Is it worth changing the oil at more frequent intervals (9k rather than 18k)?
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With pretty much any diesel it seems that as soon as you start the engine after an oil change the oil goes black. As long as it's got the correct spec oil in it should be fine. 18k between changes, unless the oil is specced for that interval, is quite a long while however.
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Yup, as Soupy says it's normal for a diesel to black its oil almost instantly.
Opinions vary, but I personally consider 18k too long for a diesel engine to run on the same oil. I had a Scenic 1.9dCi on 18k service intervals, and used to do a DIY oil change half way between. On those engines, Renault themselves shortened the intervals to 12k on later cars, which spoke volumes to me.
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Without doubt i would go for the 9K intervals Fothers, and i'd use decent stuff too, though chances are it will as black as bills mothers within ten minutes of changing.
I didn't reply to your rattle thread but i did have lurking in mind it wouldn't hurt to throw an oil and filter change in anyway, unless you are convinced that it had pukka oil and not some £7.99 mazola thrown in.
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>> With pretty much any diesel it seems that as soon as you start the engine
>> after an oil change the oil goes black.
Doesn't that indicate particulate contamination of the oil?
Last edited by: L'escargot on Wed 21 Jul 10 at 14:33
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No, it means the oil is carrying the soot particles in suspension - which is exactly what a diesel engine's oil should do. It's quite normal for the oil in diesel engines engines to turn black almost straight away.
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The oil only goes black straight away when all the old oil hasn't been drained properly.
When I change the oil in my diesel Passat I make sure all the oil is sucked out of the filter housing. I use a pela pump for this job. The new oil stays clean for quite a time.
When I change the oil on my tractor the new stays clean. I have never agreed with all these "the oil goes black straight away" comments.
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>> When I change the oil on my tractor the new stays clean. I have never
>> agreed with all these "the oil goes black straight away" comments.
>>
Depends on the car in question, my Toyota Diesel pick up stays clean for months where the family BMW 320d turned black immediately despite being able to fully empty the filter chamber, both fully drained hot via sump plugs...the BMW you would swear the oil hadn't been changed within 2 minutes.
Some engines drain properly where others leave pools of dirty oil in recesses ready to colour the fresh.
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>>I have never agreed with all these "the oil goes black straight away" comments.
The oil in a diesel engine is designed to hold soot in suspension, and the oil turning colour signifies nothing whatsoever. Yes, some engines drain more completely than others, and the oil stays cleaner for a bit longer - so what? The oil turning black straight away certainly doesn't signify that anything is wrong - quite the contrary.
In fact, if you used the wrong oil, one with insufficient detergent and soot holding properties, it might stay clean looking for longer.
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>> I use a pela pump for this job.
I'm thinking of getting a 2 litre version. Where's the cheapest supplier?
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I bought my Pela from ebay. It is a good tool, I change the oil in the Passat and Golf using it. When it starts sucking air I put a bit of new oil in and then suck this out. The result is nice clean oil for a while.
I know that this subject has been discussed on either this site or the other, but I think that it is much easier sucking through the dip stick than grovelling under the car trying to get the undertray off and undoing the sump.
Use the wrong oil? Not me guv, I'm obsessed with using the correct oil!
Last edited by: Quizman on Thu 22 Jul 10 at 16:09
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>> I know that this subject has been discussed on either this site or the other,
>> but I think that it is much easier sucking through the dip stick than grovelling
>> under the car trying to get the undertray off and undoing the sump.
I agree fully. I think that when you use a Pela, or similar, it means that it is more likely that the car gets an oil change on time, or even early, as it's such an easy and clean process.
>>When it starts sucking air I put a bit of new oil in and then suck this out. The result is nice clean oil for a while.
Straying into oilrag's territory, I'm sure the oil staying clean for a while longer makes you feel better, but, it's really just a waste of oil.
>> Use the wrong oil? Not me guv, I'm obsessed with using the correct oil!
Wise fellow!
I bought my Pela, which has 6 litre capacity, from a boating shop, although I expect that there are cheaper sources now they're becoming more popular.
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My Pela copy came from Screwfix - competitive to what I saw on ebay and no messing around waiting for delivery.
The oil on the CC3 has been changed twice, once by me and once by the dealer.
Both times it turned black straight away.
There's nothing wrong with the engine, and I'm certain the correct oil was used the second time, if not the first.
The only conclusion is some diesels blacken their oil quickly - the reasons given by NC for this seem like common sense to me.
Last edited by: ifithelps on Sun 25 Jul 10 at 07:47
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On my engine, there's an oil cooler where the oil gives its heat to the engine coolant - this isn't drained however you do an oil change - there's also the contents of the oil pump and the oil galleries which are under pressure while the engine runs - these tend to remain full of oil.
Anyone who's ever stripped a diesel engine down will know that inky black oil remains trapped in parts like recesses for bolt heads, inside the hex of socket head screws, inside the base of valve springs, etc, etc.
The oil turns visibly black even with a small amount of soot in it, and until the soot loading becomes such that it begins to increase the viscosity of the oil it isn't harmful. In older indirect injection engines which didn't burn particularly cleanly, it was this soot loading which forced a short change interval, and still does if you have something like a MB W123 diesel with a very old tech OM617 engine, but, with the modern engines being much cleaner burning, this issue has become less important.
The upshot is that visible blackening of oil in a diesel engines means nothing - there are more important things to worry about.
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...there's an oil cooler which isn't drained however you do an oil change...
Another good point I'd not thought about.
To drain the oil cooler on the CC3 you'd have to disconnect it, pick the car up by its back wheels and shake vigorously.
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>> To drain the oil cooler on the CC3 you'd have to disconnect it, pick the
>> car up by its back wheels and shake vigorously.
I think the CC3 would break its back at such treatment.
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...I think the CC3 would break its back at such treatment...
Possibly, but at least I'd get to see the two rollover protection bars pop up behind the rear seat.
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>> When I change the oil on my tractor the new stays clean. I have never
>> agreed with all these "the oil goes black straight away" comments.
One of my diesels arrived new from the factory with 75 miles on the clock. I checked the oil at 200 miles and it was black. How does your "old oil not removed theory" stack up to that?
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They possibly used old oil at the factory.
What make of car was it?
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VW just like your passat.
Of course they used old oil at the factory (not)
Last edited by: Zero on Mon 26 Jul 10 at 17:27
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I can't understand it. I changed the oil on the Passat about 2000 miles ago and it is still clean. Perhaps my eyes are going.
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...and it is still clean..
Must be the good, fresh country air.
Probably not, but when I was in London, my shirt collar and cuffs used to turn black in a day.
Never happened when I was in the country.
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I would love to know which muppet in VW's engine design team specified the use of a black dipstick on their diesel engines. Jet black oil against a jet black dipstick. Annoys me every time I check the oil on the Golf.
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I disabled the EGR valve in my car, and now new engine oil stays golden/brown for weeks, whereas it was instantly black before.
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FIAT Scudo - 04 2.0 Engine oil black. - Soupytwist
