# Brown engine oil?



## chuckinduck (May 28, 2003)

Winterized my boat today and my buddy was over. When I pulled the filter the oil was a darkish brown. Not black. He thought it looked odd. I told him it was that color last year too. I have usually taken my boat in for winterization so I don't have a basis for comparison beyond last year. Should all motor oil be black when it breaks down? Thanks for any feedback.


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## auger (Mar 6, 2013)

Did mine today in direct sunlight, completely black. It was last changed in the spring. Hope this helps


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## Quack Addict (Aug 10, 2006)

chuckinduck said:


> Winterized my boat today and my buddy was over. When I pulled the filter the oil was a darkish brown. Not black. He thought it looked odd. I told him it was that color last year too. I have usually taken my boat in for winterization so I don't have a basis for comparison beyond last year. Should all motor oil be black when it breaks down? Thanks for any feedback.


Color of used engine oil depends on A LOT of things. How many hours on the oil, hours on the engine, usage (cruising, trolling), type of engine, type and brand of oil, temperature of the cooling water, condition of the cooling system, the type of fuel used (straight gas or E10), etc. Color of used oil is a bit like reading tea leaves.

Bottom line is always change your oil in the fall when you winterize. 

The only thing brown oil tells me is it wasn't run as hard or as long as it could have been, which is a good thing.

If the oil looks opaque and milky, there are problems...


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## auger (Mar 6, 2013)

I should've elaborated more. I ran my boat a lot this year and could've/ should've changed the oil a second time. What he said^^^


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## chuckinduck (May 28, 2003)

Thanks guys. I wouldn't call it a hard 50. Most of it ( probably 40) was trolling hours. I run a 25w-40 mercury oil and just 89 grade gas. I did some reading on brown oil and obviously water or gas/coolants mixing would be the fear. Seemed like everyone described milky oil as the color of coffee with cream or tan in color. Neither would be how I would describe my oil. I did save the oil to see if I see separation.


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## ESOX (Nov 20, 2000)

Opaque brown oil is just lightly used oil from an engine that isn't running overly rich.


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## wyandot (Dec 5, 2013)

chuckinduck said:


> Winterized my boat today and my buddy was over. When I pulled the filter the oil was a darkish brown. Not black. He thought it looked odd. I told him it was that color last year too. I have usually taken my boat in for winterization so I don't have a basis for comparison beyond last year. Should all motor oil be black when it breaks down? Thanks for any feedback.


That's how it should look. If there's any significant amount of gas in it,you can smell it. If there's water in it, it will look like coffee with a lot of creamer, and it will be thicker, lots of water, it'll be thick to the point where it won't even drain. The oil in a sea-water cooled marine engine doesn't get as hot as a car, that's mainly why it isn't black.


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## chuckinduck (May 28, 2003)

Ok guys. Thanks for your insight. I appreciate the feedback.


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## Quack Addict (Aug 10, 2006)

Until this year I was putting about 300 hours per season on the v8 in my boat. Added a kicker this past spring so hours on the main went way down. After 300h of use my oil would be dark brown, not black. This year it looked almost like new oil when I drained it.

The filter is just as important as the oil and many guys just put an 'el cheapo filter in. We aren't in salt water so I see no need for a $tainle$$ "marine" oil filter. Cheap automotive filters have less filter media and the filter media is more porous so they allow more crap to pass. Use good automotive filters. Water in the oil destroys most filter media causing the media to break apart and become debris in the oil. Oxygenated fuel (ethanol in it) is the bane of marine engines. The alcohol itself has some water content to it from the pump and it absorbs more as it sits in the fuel tank. The water turns to steam during combustion and gets into the oil thru blowby. You also get really nice acidic byproducts from ethanol combustion that end up in the oil. I go out of my way and spend the extra $ to put non-ethanol gas in my boat. I wish they never started putting that crap in pump gas.


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## john warren (Jan 25, 2005)

id say its fine. might even be a bit of condensation in there adding to the brownishness. but boat motors often don't get enough hours to turn it black.


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