I need to put in a cup, maybe a pint between changes... say 3500-4500 miles or so. Using Mobil1 5w30.
I did lose oil rapidly once before into my cooling system (though no water in the oil) while using a certain cooling system additive... though curiously the oil loss did not occur when using regular coolant without the additive. To be sure, I flushed the coolant with a block sealer as well as used a crankcase sealant before oil change and problem has never happened since (over a year). Never did try that coolant additive again...
As for oil burning, not much more than the cup or two I mentioned.
