The best way to avoid a very common engine oil oxidation source, is to let the engine shed the heat from the piston crown, by idling it for a minute+ before shutting it down. If you came from a highway, running at 85mph, put the car on the rest area and shoot the engine down, that's a nonono. You can get about 150F temperature decrease with that practice and won't boil the oil in the ring pack area every time you turn the engine off. That heat will go to the coolant and you'll feel the engine hotter, but the pistons,rings and the accompany oil, will not be hotter. Such oil boiling makes the most crud on mineral oils. while the engine is running tha volume is constantly changed by fresh or cooler oil. And, rememmber at shut down, that every 10 degrees of temperature hotter, will cut the oil oxidation capacity to the half, imagine that volume at 400 instead of 250 ... That volume (about one ounce or so) could be toast by a bad practice.
Synthetic oil withstand much better this condtion, but why stress the thing ...
You get the oil a little darker (by oxidation stand point, not for the cleaning agent detergents), every time the engine don't get the excess heat spread form the pistons (the main heat source) to the coolant. Yes, what makes oil darker is also the shut down.
Critics, come by, and have coffee...
Synthetic oil withstand much better this condtion, but why stress the thing ...
You get the oil a little darker (by oxidation stand point, not for the cleaning agent detergents), every time the engine don't get the excess heat spread form the pistons (the main heat source) to the coolant. Yes, what makes oil darker is also the shut down.
Critics, come by, and have coffee...
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