Black sludge under oil cap, no white

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mrmeme1212

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Greetings Brains trust,

Got an 07 D40. Was having a look at fluids today and there's some thick black sludge under the oil cap and underside of rocker cover. No whites in it and the coolant level is stable. I've got a catch can on it which has a bit of gunk in it, I've moved to a cold climate and I only really do short trips most of the time so that's to be expected, but I'm not sure what could cause the black sludge in the engine. Oil change before last I put a can of carbon cleaner through the intake and got a lot of crap out, do we think it could just be stuff coming off after the fact from that? Was thinking of putting some seafoam or what ever it's called through it and doing an oil change (not due for another 2.5k km). What do we think?

Cheers,

Jay
 

Old.Tony

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Black in the oil of a diesel is normal. They produce a lot of blow-by and part of that blow-by is soot. It's unavoidable.

A good engine flush during an oil change might help. I've heard of Seafoam for the carbs on my bike but never for the crankcase, learn something new every day. I would trust their products.
 

johnl56

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I always thought sludge was due to lack of oil changes. It could be also change in climate as well, colder climate may affect what weight oil you put in it. Might pay to do a flush
 

KevinE

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I always thought sludge was due to lack of oil changes. It could be also change in climate as well, colder climate may affect what weight oil you put in it. Might pay to do a flush
That's what I thought too.

My wife used to have a BA Falcon & trying to get her to commit to having it off the road for an oil change was near impossible. By the time the oil was changed, the old oil usually looked like Vegemite lol.
 

mrmeme1212

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I'd think that while black oil is normal, black sludge wouldn't be?
That was my concern, could be running too thick an oil I guess. Definitely not overdue for a change, I do them regularly. I'll be doing one next weekend though before I drive back up to Sydney.
 

KevinE

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I found this on line

It seems to make sense?

I've been using Castrol semi synthetic for an extended period & have actually had the reverse. The oil is thinner when I change it than it was when I put it in there. It's also full of ash. I can feel it when I take the sump plug out, it feels gritty.

I just had it done by Oil Change Express for the first time & they used Mobil full synthetic. I'll have to keep an eye on what's happening, as I do lots of short trips.
 

mrmeme1212

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I found this on line

It seems to make sense?

I've been using Castrol semi synthetic for an extended period & have actually had the reverse. The oil is thinner when I change it than it was when I put it in there. It's also full of ash. I can feel it when I take the sump plug out, it feels gritty.

I just had it done by Oil Change Express for the first time & they used Mobil full synthetic. I'll have to keep an eye on what's happening, as I do lots of short trips.
Yeah that makes a lot of sense, cheers. I'll put some cleaner through it for a week or so before I change the oil.
 

Phunk

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One thing I used to believe was that when an engine got higher in KM's it was better to start going thicker oil.

In chatting to an engineer at some stage, he set me straight and told me it was a myth. If you have a healthy engine stick to the OEM recommend viscosity as the engine was engineered to run that oil.

I only ever use Nulon or Castrol (depending on the sale price) 5-30 full synthetic.
 

Erick

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No need for higher viscosity oil. Change it more often if ur getting sludge. New engines don’t wear so much as get increased ‘blow by’ past the rings and valve guide seals.
 

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