Recently got this car which has 140,000 miles and will be doing an oil change soon after running 1000 miles with a pint of Kreen in 10W30. The OP gauge is usually down to one or two bars at warm idle. Yesterday while stuck in bumper to bumper traffic for a half hour it would drop to no bars. (coolant temp is at 3/8) I didn't get any warning messages so assume it was OK. Is it? Gauge goes to 3 by 2000 rpm or so, and on cold starts it's at 3/4 so I think the sender is good. Thinking of going to 10W40 or 10W50.