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Dirty derv oil?


Dick Longbridge

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A garage did an oil and filter change on Mrs Dicks dirty derv a week ago tomorrow.  Prior to the change, I lobbed a tin of Wynns engine cleaner in and sat in the car with the engine ticking over for fifteen minutes, as I always do with this particular motor.

She's done around 140 miles since. 

I checked the oil level for the first time today and this is the colour of the oil. I appreciate diesels are filthy bastards, but is the oil really likely to have become this grim after such a small amount of use? The fact the engine had oil treatment thrown in before the old was supposedly dropped out should have helped with getting rid of most of the old muck as well. 

Thoughts? I feel a phone call being made tomorrow morning...

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Absolutely normal.

Oil in the van was inky black within minutes of going in - I was actually quite worried that the innards would be full of varnish and sludge...however this is what greeted me when I pulled the cam cover off to replace the leaky seal.

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Yep, the oil is black because it's keeping everything else clean it seems.

Just keep the change intervals sensible and use appropriate oil (the oil for diesels does have added detergents compared to the same grade for petrol engines I believe) and it should be fine.

Oil being black on a diesel is fine, so long as it's black and the right viscosity...not diluted to being water thin due to fuel contamination in particular...

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56 minutes ago, MikeR said:

Yep . My zaffy was like that .. the oil just felt newer ..

 

49 minutes ago, TrabbieRonnie said:

My old Surf's oil looks like that after five minutes!  As others have said though, you can feel the difference in the engine. 

I'd actually be concerned if I noticed a difference, as that would suggest I'd allowed the oil to deteriorate to a point where it was no longer protecting the engine effectively.

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Just now, mat_the_cat said:

 

 

I'd actually be concerned if I noticed a difference, as that would suggest I'd allowed the oil to deteriorate to a point where it was no longer protecting the engine effectively.

I change the oil every 5,000 km's (as per the book, approx. 3,000 miles!), and have owned the (28 year) old girl for six years and coming up on 120,000 clicks... I don't think I'm far wrong.  We're just very much in tune with each other!

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Thanks very much everyone. I never intended to phone the garage until I'd asked for other opinions. Its reasurring to know that our dirty derv is soiling itself just as it should. 

Interestingly, we did comment how our car sounded a bit quieter after the oil change although wondered if it was just the mind playing tricks. It's been 11k since the last oil change, so just under the 12k suggested by the fuhrers. 

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I’ve only ever seen ONE Diesel engine with clean oil. Mate of mine has an E39 530d with 240k up it. He flushes the oil by draining it, filling the sump with red diesel to the minimum mark. Runs the engine for 5 mins then drains and refills with fresh oil. Never seen a Diesel engine oil so clean. 

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I’ve seen the oil in my 258k Partner Combi HDI be clean like a petrol engine after several changes at the 2.5k mark when it came out of storage a couple of years ago. 
After a couple of years of 6k changes it’s fully black and still looking black-ish straight after a change.

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Thanks for the reminder though...I got the oil and filter in to change the oil in the van a month or so ago and proceeded to stuff it in the locker under the wardrobe and immediately forget about it...

 

Let's get that changed and see how it goes!  In this case it's always going to be hard to get it fully clean because A: it holds nearly eight litres of oil, and B: there's no way to fully drain the oil cooler (which is about the size of a K10 Micra radiator) and the lines to it. 

Interesting though as it's one of the cleanest running diesel engines I've ever known in terms of smoke, so the detergents shouldn't realistically have as much work to do as in a lot of modern engines...

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10 hours ago, Isaac Hunt said:

I’ve often thought of pulling the new oil out after a couple of hundred miles and re-filling to see how long it takes to get ‘back to black’.  I’ve never got around to it.

I wouldn’t waste your hard earned cash. I had to change the oil in my 300tdi in quick succession (24hrs and about 5 miles done) and still went black as the ace of spades real quick. Runs sweet as a nut though. 

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My van's oil is usually black by the time I get it home from the garage. The fist time I checked it about on an older van about 15 years ago, I was gonna ring up and kick off. I'd used the same garage for over 20 years and know now without a doubt they wouldn't rip me off.

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9 hours ago, cobblers said:

Every diesel I've known would turn the oil jet black within 10 minutes, apart from my new caddy which despite having it's second oil change at 38k (in line with VW service intervals) 2k later, the oil is still pretty clear.

Mental this long service interval stuff isn’t it - my Citroen Relay is 2 year / 30k!!!

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Did they drain the oil or suck it out the dipstick tube ? Imo draining it is more likely to get rid of the crap that's been dislodged by the treatment fluid.

I also never ever leave oil changes until the recommended service interval. That's jackanory bollocks for the fleet managers. 5k miles max. for semi synth and I might let it get near 10 for fully synth expensive stuff.

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15 minutes ago, Kiltox said:

Mental this long service interval stuff isn’t it - my Citroen Relay is 2 year / 30k!!!

Yeah, it puts the willies up me, it's a service interval but they only have to last the warranty period.

I'll do a couple of changes with the Pela pump in between the normal intervals.

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That reminds me, it's more than time to stain the girlfriend's drive black doing my oil.

When I was in the trade we had a few complaints that we hadn't changed diesel oil, we'd do it again in front of the customer and it would turn black immediately. 

Diesel is nasty stuff

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Same experience here as everyone else.  Diesel oil just goes black and you just can't get enough of the old out to not make the new oil black too.

Try this test next time you can.  Take 100mls of new oil, and then put 15ml of used oil in it.  Stir it up, and it will all go black.

This is what is happening in your engine.   Every engine I have ever seen cannot be fully drained.  There will be oil in the galleries, oil in pockets in the head and maybe some in an oil cooler or similar.  All of that will not drain out, meaning there is possibly 250ml of oil that cannot be drained.  Now add your 5 litres of nice new clean oil, and it'a immediately blackened by being mixed up with the 250ml of oil you couldn't drain out.

I used to notice a slight difference in oil cleanliness in XUD engines if I let it drain overnight with the oil filter removed.  You'd get another maybe 100ml of oil out, meaning the new oil had less dirty oil in it to change it's colour, but the difference was minimal.

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Had the oil changed on my 2.0 hdi picasso today (too cheap to consider doing it myself tbh)

checked it when i got home and it was pretty clean, drove 20 miles and it's starting to get dark already

i've always thought it to be normal for diesels to have filthy oil

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