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Father of 8!LordHelp'sMe!
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Discussion Starter · #1 ·
A friend was telling me that oil will turn black if over heated long enough?

Anyone hear of this???
 

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Yep, I believe it's called 'coking'. It loses most if not all lubricity, plugs up ports and once it's been burt it won't return to it's before burnt state when cooled....Mike
 

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Father of 8!LordHelp'sMe!
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Discussion Starter · #4 ·
Just another reason to change your oil if you ask me.

Now I'm wondering what that temp might just be! Most likely not the same for differant brands. Better brands having higher temps I'll just bet.
 

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All oil has a "flash point",the temparature it'll burst into flames when heated..just under that temp is when oils will break down and carbonize ..thicker oils and synthetics have higher flash points,and that is what you'd want in an old engine that burns oil--the higher the flash point the less oil will be consumed..

I'm surprised air cooled engines dont just BOIL the oil,I would think they should have added cooling fins to the crankcase,but evidently aluminum dissaptes the heat enough so it wont..
 

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if i remember correctly dino oil starts breaking down at about 300 degrees, where as synthetic oil doesn't start breaking down until around 450 degrees.
 

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Some engines do duct some cooling air under the crankcase for additional cooling. After cutting the lawn with my 16G (when it was still growing b4 the drought), I checked the CC temperature when I was done, it was 185 degrees on an 85 degree day. That is with a fairly light load, would probably be higher in the spring when the grass is thicker. This is on a Kohler Magnum 16 twin, I should add.
 
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