ok, here is one of those questions that seldom gets raised. When changing the engine
oil, it makes sense to drain the
oil cooler as well. If the
oil is not drained from the cooler, not only are you leaving at least a quart of dirty oil, but when you switch grades of oil (winter vs. summer) you'll have a mismatched quart flowing through the crank case. On the flip side, if you drain the oil cooler, ideally you should refill the cooler first before adding oil to the valve covers. Not sure you want to crank the engine with that big pocket of air in the cooler. Curious as to what folks do in this case. I think if you run the all season 10-30 or 10-40, you can keep one quart of the old in the cooler and with 8 quarts in total, you dilute the residual oil to almost undetectable, especially with that new filter you just spun. Any thoughts on this?