Black oil

[ahal]

Hi everyone,

Well, I now do my own oil but for those in the know, I have a few questions. First off, my own car. When I finally decided to do it myself, the oil that came out of the car was like black coffee. I was amazed at how dark it actually was ( looking at it on the dipstick indicated medium blackness, but there you go ). The car had only done about 2,000 miles since the local guy changed the oil!

Since I did it myself, no such problems. My main concern now is the father's 440. Same fella did the oil, and his went pitch black under the same mileage too. Not only that, but it sprung a leak, apparently aft of the splash - guard ( it's hard to tell for sure, as the car is parked nose - downhill ). I put on a new drain plug / seal when I was doing the oil, and no leaks yet.

It's been suggested to me that the guy who did the oil changes on both might have dumped in diesel oil. I've been told that this runs black quicker. Is that so? In fact my main worry right now is, does Diesel oil run particularly thinner, hence perhaps the ( pretty bad ) leak in my father's car? His is a '97 model, with less than 80k. miles.

Any ideas appreciated.

Regards,

anthony.

[Paul240480]

The oil should go black after time. Show's its doing its job. Wether yours is going black quicker then others, not sure I'm afraid.

Don't take this the wrong way, how well do you know the 'fella' who did the oil change? If he's a good friend/ someone you trust, no offence meant to you or him.

I used to have a 240GLT. The previous keeper put Diesal oil in it for years, said it had more cleaning detergents so was better (rubbish IMHO). No damage was caused though.

If I was you, for your piece of mind I'd change the oil & sump bolt washer in Dads car & see what its like after another 2k & go from there:thumbs_up:

4 series lumps, as you probably know do leak. My 480 has had a weep for years, been advisory at last two Controle Techniques. I'm gonna put a sealant in at next change. There are some very good products available for this thesedays.

Good Luck

[Mike1967]

When I owned my 240 that ran only on LPG the oil in that NEVER went black . It stayed a golden colour for many thousands of miles .

[Paul240480]

Ooh er! I've never had a car do that, ever?

[ahal]

Don't take this the wrong way, how well do you know the 'fella' who did the oil change? If he's a good friend/ someone you trust, no offence meant to you or him.


Thanks for the pointers guys ...

No worries Paul,
My local mechanic got seriously ill, now recovered and he's absolutely not able to do cars anymore ... which he doesn't realize. Nice guy, but just not up to it anymore and tends to make a b***s of stuff. Been using the same guy for years without a problem 'till recently. He's an old boy who won't be happy 'till he's found dead in an engine bay ...

Cheers,

Anthony.

[GTMaster]

It's true, that diesel motor oil goes black quicker, but otto(4 stroke) engine's oil shouldn't go as dark (probably something like dark brown, near black). LPG engines run cleaner, that's why i'd suspect the oil stayed the same colour.

[B20F]

Diesel oil contains more detergent additives. It cleans better than petrol oil, hence it darkens quickly when you first use it in a car that always had petrol oil in it. I would change it, probably the oil stays clean much longer now that all the sludge is removed from the innards of the engine. And don't forget to change the oilfilter! Diesel oil doesn't do any harm to a petrol engine, some say it's even better for a petrol car.

[Paul240480]

Diesel oil doesn't do any harm to a petrol engine, some say it's even better for a petrol car.

My 'old fella' used to be a manager in a very big american oil firm. They only made addatives. As in Mobil, or Castrol, or BP etc made an oil that just would'nt quite do exactly what they wanted. So they turned to the company my old boy worked for & they then spent many an hour fine tuning the oil, testing it & selling the oil (addative included) back to the original maker.

Their opinion was that diesal oil would'nt do harm to a petrol engine, but it is certainly is no better. If it was they'd have promoted it as such.

You correctly say B20F it'll do no harm.

[GavinC]

My experience and observations with oil with different fuels:
LPG burns so cleanly that the oil stays golden - almost the same colour as new.

Petrol burns much less cleanly and so the oil starts to darken after a thousand miles or so. If - unusually - I run my LPG car on petrol and pull the spark plugs, I expect them to be significantly darker and 'dirtier' than if I was running on LPG. The exhaust tailpipe shows the difference, too - and you can tell the difference by running your finger round the inside of the pipe.

When I change the oil on my diesel car, it gradually turns pitch black in less than 1,000 miles. Diesel produces so much carbon that it requires higher detergency oil. Modern diesel engines have 'particulate traps' to clean the exhaust emissions of fine carbon. Run your finger round the inside of the tailpipe of a diesel car - particularly older types without particulate filters/traps - and you'll get a lot of soot on it.

[keithyboy]

When you drain it, give it a bit of a sniff to see if it whiffs of petrol.

If it's turning black really quickly, it might indicate that it's running rich and too much petrol is mixing with the oil.

[NI_Volvo_Nut]

The blackness in the oil is the carbon by-products. Hense why on lpg it stays clean, no carbon.

[ahal]

When you drain it, give it a bit of a sniff to see if it whiffs of petrol.

If it's turning black really quickly, it might indicate that it's running rich and too much petrol is mixing with the oil.

Thanks Keithyboy,

That's spot on actually. When I was disposing of the oil I noticed a distinct petroleum whiff off of the oil. The car consistently acts the b*****d on me around town: a sudden stop results in it fighting for life / stalling.

I always re-starts though, and will drive all day just fine ... until I get to a town. I give up on that problem altogether, I've decided to just keep on driving it. The robbing hoors in the garages around here just see it as a means of getting money for damn all. I'm sure lots of garages could fix it, they just don't want to ( moral of the story "buy a new car from us" ).

It's a long standing problem, and I posted a thread about it approximately a year ago. Hasn't improved or got worse in that time. I'm up from 73k. in 2001 to 149,500 right now, so it's doing the biz otherwise, and quite frankly, I don't trust any garages in my area at this stage.

Strangely, it's super - economical too!

Cheers,

Tony.

[jlgrosvenor]

If you use a quality oil with good detergent properties (after using a lesser oil) then when the good/better oil is used it will clean off a load of crap in the engine. This will happen over thousands of miles if poor quality oils have been used for a long time, as there will be a lot of crap to clean off. Also, newer oils are not friendly to older gaskets, or rather, older gaskets were not designed with the newer oils in mind (they weren't around at that point). After changing to Mobile1 (£23.44 from Costco Cash & Carry) I got a lot of black oil out. I also sprung several leaks from the engine. These were the sump seal, and the rear crankshaft seal. I was losing about 2 litres of oil every few hundred miles, but if the car was stood without running after filling with oil, it would just sit in the sump. I had to remove the engine and replace all the seals on the block. Now, no oil leaks.

This is a common problem on 440s, and explains the difference you will find if you do change the crankshaft seals and compare the old ones with the new designs.