Black oil?

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Longgone

Longgone

John/68 Barracuda & Dart
Joined
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I`ve had an issue for the longest time with my oil turning black (getting dark) very quickly even shortly after an oil change. I knew it wasn`t dirt inside the engine as the rebuild was not that long ago. I had thought the worse although the engine was running fine and held good oil pressure. Today I believe I found the culprit. I was adjusting the valves and was about to put the valve cover back on when I looked at it, (as it sat upside-down on the fender), lo and behold there`s several notches cut out of the black rubber gasket. Evidently the valve springs have been chewing away at the gaskets and sending small pieces of black rubber all through the engine. I`m hoping that nothing`s been clogged up by these particles. I haven`t noticed any drop in oil pressure. New gaskets and an oil change and so far, so good.

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I doubt that that is the cause of the black oil....however,not a goodthing either and its good that you caught it.....if anything you may notice a few small black flecks floating on top of your oil that are pieces of the valve cover gaskets.....get a good set of rubber felpro gaskets,they work good!. the culprit of the black oil could be a large number of things!!!one of the smaller things it could be is your choice of oil filter.......it could be build up engine sludge in your oil pan/block/heads and all other internal areas. Over time piston rings do SLIGHTLY shave the insides of the cylinders but nothing so rapid or anything that your going to drop compression or wear out your rings in no time....its a very minimal and slow process and just enough to contribute to the black color of your oil.....most engines can go 100,000 miles before even having to think about rings or cylinders wearing out......another thing it could be is bearing wear.....your choice of oil....bad ventilation (pcv)....if you have slightly worn rings and run to rich of a fuel mixture,unburnt raw gas can make its way into your oil....smell your oil and see if it smells gassy and that will give you a better idea on that one......but for the most part,what your dealing with is a common thing and most likly won't need to worry of any damage going on or anything....but just for the heck of it and to be sure....try switching oils,filter,new spark plugs,make sure your carb is tuned,make sure you have a good breather vent, run a compression check,smell the oil.....mostly easy and basic and cheap stuff and should be considered routine maintenance.....hope anything I had to mention might be of some help for you!
 
This engine only has about 2000 miles on it. It`s always had K&N oil and air filters and Valvoline VR-1. I started with Fel-Pro cork valve cover gaskets but with solid lifters I needed something reusable so I changed to the Fel-Pro rubber. That`s what`s shown there in the picture but the tabs got burnt off by the headers. I hope the gaskets were the only issue and that from here on out it`s smooth sailing. I might be exaggerating when I say "black oil" but you can see the oil in the valve cover and it seems awful dark for only 1000 miles on it? The car runs like a bat out of hell, a little rich but the oil is not smelling of gas. I need to go put some miles on this thing and see how it goes.
 
I didnt notice those were rubber gaskets.....my local parts store sells rubber felpro gaskets but they are bright blue.....anyhow,thats your problem right there! lol......with only 2,000 miles on the engine......its still breaking in! you just need to wait it out...it will get cleaner as more miles and oil changes are put on it. its just now letting the pistons cut a groove into the cylinders and all your bearings are wearing into the rotating assembly,not to mention if you used assembly lube (wich you should have during a build!!!) that stuff will keep your oil dark for a few oil changes worth. anyhow,I don't think you have anything to worry about,just make sure your carbs tuned in good and that your ignition system and timing are all up to par.
 
I thought maybe I hadn`t cleaned the engine thoroughly enough since it had a lot of machine work done. I`m just going to watch the oil pressure gauge and have fun. I believe it will get a little better with a couple more oil changes.
 
Longgone said:
I thought maybe I hadn`t cleaned the engine thoroughly enough since it had a lot of machine work done. I`m just going to watch the oil pressure gauge and have fun. I believe it will get a little better with a couple more oil changes.
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yup...I think your right,should clear up with a few more oil changes,just doing the normal wearing in and it gets a little dirty during that point of the process.....2 more oil changes and it should be close to golden!,good luck
 
Longgone-
What compression ratio does that motor have? High compression engines will darken the oil up pretty quickly.
Personally, it doesn't look too dark from here judging by the picture.

Good Luck.

George
 
That's not black oil to me. VR-1 looks like what you have on the valve cover straight out of the bottle. You can still see through the oil.
 
That's a new one. Here's an idea, Write a letter of inquirey to the mfgs of whatever brand of oil that you use. " Can I expect engine problems or have I discovered the next great additive ?" Good luck
 
George R said:
Longgone-
What compression ratio does that motor have? High compression engines will darken the oil up pretty quickly.
Personally, it doesn't look too dark from here judging by the picture.

Good Luck.

George
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Good point, George, about high comp. Hence the reason diesels always look like dark molasses at oil changes. (That and sulfur...but I digress.)
 
George R said:
Longgone-
What compression ratio does that motor have? High compression engines will darken the oil up pretty quickly.
Personally, it doesn't look too dark from here judging by the picture.

Good Luck.

George
Click to expand...

Close to 11-1 George, maybe you`re on to something there.
 
High compression isn't as much to do with it as ring seal, and combustion pressures. A low compression engine with a turbo or blower would have the same effect. Or even a low compression engine that runs WOT a lot.
Example, when I first got my Cummins, it was a stock 160HP motor, the oil would stay clean for 2K miles, with 12 pounds of boost, now, it is over 350HP, and runs 45-50 pounds of boost, and the oil is black the first time I boost it up. Basically it is combustion gas making it past the rings.

If you had a good hone, and quality rings, installed right, don't be suprised if it cleans up as soon as the assembly lube and break in junk is all gone.
 
Well I hope you guys are right, at least I no longer have gasket material floating around in there to contend with. Like I said, I`m going to drive it, have fun, and see what gives after a couple oil changes.
 
Crude oil from the ground is black 8)

I know what you mean thou, have an F.I.15 year old car with 150,000 miles and looking at the dip stick the oil looks nice and clean til the next oil change, were my carb motor that runs heavy turns the oil black a few weeks time.

But both motors are running fine, carb motor is 8 years old and like 35,000 miles. When I change the valve covers this weekend it was nice and clean looking


I was told long ago take the black oil and put it on your fingers, if you can see your finger prints, the oil is clean.
 
I'm going to go agaisnt the grain here... If you have moly rings and the proper bore finish for them, and if they were cleaned well during assembly... They would have been 90% seated during the cam break in, and 100% after the first 5 miles of driving (under load). Most shops I have seen leave too rough a bore and ring seal is a problem. If you are running it rich, that's your black oil. It's also why deisels go black fast. It's soot and carbon from running rich making it to the oil. Your engine should be totally broken in and the oil should be new looking, especially after two changesz in 1K miles. The cam lube is gone. The moly is removed as it gets trapped in the filter and can plug it causing the system to by pass. So tune it to get rid of the rich, and if you're really curious do a leakdown. If you have leakage higher than 5% but less than 10% you probably had too rough a bore finish or too high a spec of end gaps.
 
moper said:
I'm going to go agaisnt the grain here... If you have moly rings and the proper bore finish for them, and if they were cleaned well during assembly... They would have been 90% seated during the cam break in, and 100% after the first 5 miles of driving (under load). Most shops I have seen leave too rough a bore and ring seal is a problem. If you are running it rich, that's your black oil. It's also why deisels go black fast. It's soot and carbon from running rich making it to the oil. Your engine should be totally broken in and the oil should be new looking, especially after two changesz in 1K miles. The cam lube is gone. The moly is removed as it gets trapped in the filter and can plug it causing the system to by pass. So tune it to get rid of the rich, and if you're really curious do a leakdown. If you have leakage higher than 5% but less than 10% you probably had too rough a bore finish or too high a spec of end gaps.
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Boy.... that oil is getting clearer by the minute isn't it Longgone?

LOL!
 
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