Changing oil on a diesel!!

rbh · Dec 10, 2011

So today I had to do an oil change on an early 90's 7.3 diesel.
"I HATE" it when I do a fresh oil change and filter and the stick still shows black.

I think I want to do a flush next time, how many guys have emptied out the oil, installed fresh filter with diesel then filled the crank case with 5-8 pints/liters of diesel fired it up for 10-15 seconds, just to flush out the scummy old oil??

Thanks

Rob

mla2ofus · Dec 10, 2011

Re: Changing oil on a diesel!!

I personally think you're asking for trouble. Not knowing what your change interval is, how about just changing oil more often?
JMHO,
Mike

86 century · Dec 10, 2011

Re: Changing oil on a diesel!!

I thought the same thing with my '84 6.9 so I ring up my brother the diesel guy(was a tech the went to school and the bit for diesles)he just laughts and says it doing its job. In my case the eng had close to 400k on it.
Good luck

Bondo · Dec 10, 2011

Re: Changing oil on a diesel!!

Ayuh,... Is it a PowerStroke, or Idi,..??

Black oil in a diesel ain't necessarily a bad thing...
Just changin' it in a timely manner is all that's needed,...
Fushin' the motor with fuel will just cause Bigger problems anyways...

r.j.dawg · Dec 10, 2011

Re: Changing oil on a diesel!!

Bond-o said:
Ayuh,... Is it a PowerStroke, or Idi,..??

Black oil in a diesel ain't necessarily a bad thing...
Just changin' it in a timely manner is all that's needed,...
Fushin' the motor with fuel will just cause Bigger problems anyways...

+1... Diesel engines need more oil changes than their gas partners. And as Bond-o said, please don't flush. Do an oil change, run for about a 100 miles and change again. That should clean it fine.

MRS · Dec 10, 2011

Re: Changing oil on a diesel!!

Nooo, oil only if anything run some cheap oil and maybe add some marvel to it for a hundred or so miles then drain and do again. Way cheaper than a rebuilt.

Alan_Scott · Dec 10, 2011

Re: Changing oil on a diesel!!

If you have a Powerstroke, you can also pull the top plug on the high pressure oil pump (hpop) reservoir and vacuum out even more old oil. You'll have to refill the hpop separate from the crankcase, otherwise it won't start without excessive cranking.

Side note: if you replace the engine oil with diesel, a Powerstroke would die as soon as the diesel in the crankcase reaches the hpop because then it couldn't build enough pressure to fire the injectors.

tomdinwv · Dec 11, 2011

Re: Changing oil on a diesel!!

I was a mechanic for a transit authority and we had about 15 Ford cutaway busses with the7.3 Powerstrokes.. Changed the oil in them about every 3k miles. We never had a problem with the engines in those vans. Their "service life" was either 200k or 250k miles. Only bad problem we had was with the automatic transmissions. These vans were heavy, and then you shove 15 or 20 people on them and they were real heavy. Most of our drivers wouldn't turn the overdrive off and would run them until the forward od gears would blow up. We'd strip those transmissions apart and it looked like someone set off a grenade in them. lol.

Just change your oil and filters at the recommended intervals and you shouldn't have any problems.

skargo · Dec 11, 2011

Re: Changing oil on a diesel!!

r.j.dawg said:
+1... Diesel engines need more oil changes than their gas partners. And as Bond-o said, please don't flush. Do an oil change, run for about a 100 miles and change again. That should clean it fine.

This is not true. I have my Cummins oil tested at Blackstone labs and they have me on a 10K mile change interval. Many people dump perfectly good oil down the drain using too early of a change, and running it for 100 miles and changing it again. Seriously, my truck takes 3 gallons of oil, who in their right mind is going to throw away 100 mile oil that is perfectly good?

dolluper · Dec 11, 2011

Re: Changing oil on a diesel!!

Like others have said just use oil nothing else...your bearings will be happier.....on gassers we change the oil after they have been flooded you know the reason why....apply that here too.....don't cause a problem....change the oil when you should and drive it......your just luckey it's not a 38 litre 2 filter job thats alot of black oil lol's

SS MAYFLOAT · Dec 11, 2011

Re: Changing oil on a diesel!!

I have an old IDI 7.3. It doesn't get the miles put on it, but it does sit and idle to run the hydraulic pump for the bucket. I change the oil once a year and the oil filter about every 3 to 4 months.

If the water in your swimming pool is dirty, you backflush or change the filter. You don't drain the water every time the water gets dirty. Once a oil filter gets too filled with debri, it will go into bypass. I suggest changing the filter more often than oil changes. BTW, always prefill your filter with oil before installing it on the engine.

JB · Dec 11, 2011

Re: Changing oil on a diesel!!

My Mercedes Benz 190 and 220 Diesels from the '60s always had black oil even after an oil/filter change. My Kubota Diesel tractor has black oil even after an oil/filter change.

MB Techs assured me that was/is normal.

skargo · Dec 11, 2011

Re: Changing oil on a diesel!!

JB said:
My Mercedes Benz 190 and 220 Diesels from the '60s always had black oil even after an oil/filter change. My Kubota Diesel tractor has black oil even after an oil/filter change.

MB Techs assured me that was/is normal.

yep, my Cummins and my New Holland diesels blacken up after you run them after an oil change. It's simply soot in the oil.

bigdee · Dec 11, 2011

Re: Changing oil on a diesel!!

What is wrong with black oil? Psychological maybe. Black hydrocarbons are ultra-slippery ie; teflon!!

puddle jumper · Dec 11, 2011

Re: Changing oil on a diesel!!

Simple NO

RogersJetboat454 · Dec 13, 2011

Re: Changing oil on a diesel!!

When I was working at the independent repair shop, we did regular service and repairs on the ambulances for the ambulance company in town. These ambulances were well cared for, and had frequent oil changes (regular maintenance in other words). No matter how often you changed the oil, the new oil you put in would always be black after starting the engine. The engines ranged from the 7.3L turbocharged Powerstroke, the GM 6.5L, the GM 6.6L Duramax, and the dreaded 6.0L Powerstroke. We all just accepted it as reality that on a diesel the oil is going to turn black.

Fleetwin · Dec 13, 2011

Re: Changing oil on a diesel!!

Accept the fact that you can't get it all out. Diesel soot turns everything black quick.

Many ignore engine hours as a guideline. If you do a lot of idling, your engine is still working. Many have no clue just how much they idle a diesel. Totally unecessary to idle todays diesels but old habits die hard.

Hours is, by far, a more realistic interval.

Industry standards are one hour equals 25 miles. Most makers call out an hour figure in the maintenance schedules, in the owners manual. Owners Manual? Whazzat, you say? It's in the glove box, still in the wrapper!

Many vehicles have an hour meter in the odometer. I know Ford Super Duty's do. If you don't have one, they are cheap and easy to install. Just like a boat!

bigdee · Dec 13, 2011

Re: Changing oil on a diesel!!

What makes the oil black is a normal combustion by-product which gets blown past the rings (blow-by). The same thing happens in a gasoline engine, you don't notice it as much. Since gas is more of a solvent it dilutes and washes oil off of bearing surfaces.......I would rather have the blow-by burnt diesel oil (carbon is an excellent lubricant anyway) in my crankcase than the invisible gas solvent.

JRJ · Dec 13, 2011

Re: Changing oil on a diesel!!

Run a good oil like Delo 400 and ignore the color.

Fleetwin · Dec 13, 2011

Re: Changing oil on a diesel!!

JRJ said:
Run a good oil like Delo 400 and ignore the color.

Plenty of good oils out there and that's one of them.

"Color" does not make for a maintenance regiment. I think you'd agree?

Changing oil on a diesel!!

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