Black Oil matters

[Mr Cerbera]

Sorry to misuse such an important social statement

BUT

had to re-drain my system coz I failed to tighten a couple of screws in the filter housing and was shocked to find the state of my Mobil 1....



Now, a couple of decades ago there used to be a product called "Flushing Oil" which I always promised myself that I would use "at some change in the future".,

As my motor has done all of 10 mins running with this new sump-full of 0W-40 I have, in fact, performed a flush but with Oil that cost me €100

I hope she appreciates this over the next 102K miles

[ukkid35]

You usually only ever change about 75% of the oil, unless you drain down everything, hoses, heads, cooler etc

So it's likely that the 25% contaminated the new oil if it was in a pretty bad state

[Imran999]

The real shocker here is the €100 that the oil cost - we pay only about €35 (here in Can) for the TVR recommended oil.

My old 911 covers about 1000 miles every summer and during the 4-5 month winter, remains touched. At the end of the winter, I drain the oil (~80% of the total volume does come out) and change it (and the filter).
Yet, it still doesn’t look great, dark dark brown is the best I can get.

I do recall using a flush 30 years ago, but haven’t since.

[Classic Chim]

2000 miles max I’ve managed on 10/40 oil before it started to go black on my old RV8 Chim engine.
Agreed above, though discoloured that oil looks remarkably clean from here.

[Jhonno]

On 3k odd miles on my oil and still golden on the dipstick.. Will see what it looks like come oil change time!

[Mr Cerbera]

Thanks for your replies chaps My heart fibrillation has slowed to a manageable level now.

I normally change between 3 - 6K, depending on what plans we embark on and I always remember the Dipstick being "Stranglers" so it was with great shock that I saw this change.

Just have to keep a more regular eye on it from now on !

and Yes, Imran, although Petrol is a good price here, Oils can be killer.
They have gone up 80% in the last few years

[gruffalo]

Mr Cerbera said:

They have gone up 80% in the last few years

How long to pop to another country to buy some at a reasonable price?

[Grayedout]

Black oil is GOOD !!

The oil is back because it has picked up all the microscopic carbon and other results of combustion and has held it in suspension in the oil using additives called dispersants and so they come out when it is drained.

If the oil stays golden then it means all the particles are scattered around your engine and have not been picked up by the oil.

Don't be scared of black oil !

[Mr Cerbera]

gruffalo said:

How long to pop to another country to buy some at a reasonable price?

33 years I've been here and never had the thought to do that !
(Apart from the UK, of course)

You're a genius

Grayedout said:

....

Don't be scared of black oil !

Thanks Graham - appreciate that.

My principle reason for shock was the fact that it had gone so black in such a short time
BUT
with all your combined advices, I realise that I should plan to do it a little more regularly.
i.e. find a cheaper international source for Mobil 1, get a lot of it and do the flushing in a more pre-planned fashion.

Thanks all

[ukkid35]

Also, most of us are wary of using 0W-40

The consensus seems to be 10W-40

Obviously this depends on location and use type as well

https://www.pistonheads.com/gassing/topic.asp?h=0&...

[Flatplane8]

Don't know if it helps but I've used Millers CFS 10/60 motorsport oil for the last 15+ years and near 100k miles. I think any good brand with the right spec would be fine though. It does go black quickly, as someone said due to the carbon build up. The only oil I have that stays clear-ish is on my LPG powered car. Because of the cleaner combustion, there is minimal carbon produced, meaning the oil stays a golden colour.

Some companies (Millers, Morris) offer oil analysis which could be interesting. I know people with larger marine diesels who send off samples and base oil change on analysis results rather than at fixed engine hour intervals.

[Grayedout]

Grayedout said:

....

Don't be scared of black oil !

Thanks Graham - appreciate that.

My principle reason for shock was the fact that it had gone so black in such a short time

The reason it went black quickly is because the previous oil had run out of dispersant additives before it was drained and so carbon particles were scattered around your engine and so the new oil picked them all up as soon it was first run.

One of the many reasons why you should change oils regularly.

[LLantrisant]

put some of the oil on a piece of white plastic....i´m sure it will not come-up so black and will still look reasonably new

[Imran999]

Incidentally, why does the oil on the dipstick always look so much cleaner than what the oil change reveals ?

[LLantrisant]

because you have ony a thin layer of oil with a light (silver) background from the dipstick.

if it shows black on the dipstick, than its time to change.

oil, even used for just 100miles, will always come-up black when drained in a deep bucket.
would you drain it on a wide flat surface, the same oil would come-up golden-transparent.