Oil turns dark quickly

[Mad_Hatter]

Originally Posted by RDY4WAR
Dark oil simply means the oil has oxidized or has some sort if additive effect like I mentioned in a previous post. It does not mean the oil is cleaning and has a lot of dirt in suspension (though it could). Heat and acidic growth are what oxidize the oil. The better the oil can resist acids (with detergents), resist oxidation (with anti-oxidants), and cooler it runs, the longer it'll stay a clear amber.

Right. And some lubes check those boxes better than others. Likewise, not every engine operates at the same temp nor have issues with excessive blow by. Some will run a little hotter, some a little cooler comparatively. Too many variables involved to establish any kind of rule - even the big oil companies say on their websites that color alone isn't a reliable predictor of serviceability. You need data, not guesswork or anecdote.

 

[PontiacHO]

PCV valve been changed recently? Check to see if the valve is actually pulling a vacuum. Pull the PCV vent hose and see if you feel a suction at idle. Sludge in the heads can stop the PCV from pulling crankcase vapors properly and that darkens the oil quickly. Do a Marvel Mystery Oil crankcase flush as well as in the intake side to clean the combustion chambers and possible free up sticky rings. Add another bottle to the fuel tank. Then run like you stole it.

 

[bbhero]

Originally Posted by RDY4WAR
Dark oil simply means the oil has oxidized or has some sort if additive effect like I mentioned in a previous post. It does not mean the oil is cleaning and has a lot of dirt in suspension (though it could). Heat and acidic growth are what oxidize the oil. The better the oil can resist acids (with detergents), resist oxidation (with anti-oxidants), and cooler it runs, the longer it'll stay a clear amber.



I agree overall...

The oil in my lady's Camry was a strange deal... I do think that the motor finally got enough heat put in it routinely enough to cause the sudden dark color and pieces of black I observed in that oil... Though I was like

The next run it was a total normal circumstance with nothing unusual taking place.

 

[ka9mnx]

Along with PCV is the engine getting up to temp. Thermostat ok?

 

[Amkeer]

Oil will turn dark over time and is normal. My synthetic oils in all my motors do this and I have had no problems with cleanliness, UOA, or burning oil.

 

[NavyVet88]

Originally Posted by ka9mnx
Along with PCV is the engine getting up to temp. Thermostat ok?


Yes. I replaced both the pcv and thermostat with OEM parts about 8 months ago.

And the oil was turning dark as described previously prior to those parts being replaced.

 

[admzn]

In my 95 Pathfinder, I replaced the engine with a JDM import one, it currently has 60k miles on it roughly. It had a Nissan filter on it when I bought it and I'm sure it was the factory one lol. It took about 5 or 6 short oil change intervals before the oil started saying clean. Oddly enough, under the valve covers looked brand new. I used Pennzoil conventional for those first changes, and now run whatever synthetic is on sale.

 

[RDY4WAR]

The High Performance Lubricants BAS oil is pretty dark right out of the jug due to it having such a massive additive package with 1.8% sulfated ash.

 

[mahanddeem]

Switching from Mobil 1 to PUP I noticed faster darkening of oil in my 09 Maxima, using same filter and same driving conditions. First 80k miles were using conventional Nissan oil by previous owner.