I changed the oil in the wife's Xterra this weekend. 6k miles on the truck and 3k on the current fill: 2.5q Pennzoil 5-30 dino plus 1q Pennzoil synthetic.
The oil came out rather dark. Darker than the factory fill at 3k and much darker than the GTX I drained out of my 60k mi Ranger, also at 3k.
Yeah, I know there are all kinds of variables involved here, but it got me to thinking. I had always assumed that oil darkened primarily from contaminants inside the engine: combustion blowby, varnish, etc. But a new car would have little of either.
So what the heck is it that makes an oil turn dark?
thx,
mr
The oil came out rather dark. Darker than the factory fill at 3k and much darker than the GTX I drained out of my 60k mi Ranger, also at 3k.
Yeah, I know there are all kinds of variables involved here, but it got me to thinking. I had always assumed that oil darkened primarily from contaminants inside the engine: combustion blowby, varnish, etc. But a new car would have little of either.
So what the heck is it that makes an oil turn dark?
thx,
mr