Yup I have been using 15W-50 for almost 2 years and have no lifter tick. Well she will tick a bit after running hard at MSR, but it stops before I am back to my parking spot. Befoer switching I tried everything with little to no results. I also use the Purelator Pure One filter for the Honda like Iain does. Not only did Mazda change the filter design and size for the Miata but so did PurelatorI like the larger size of the Honda filter and it even says it has the anti-drainback valve right on the box
Bottom line, is it is cheep insurance compared to ruining a good motor.
"Pain is inevitable, suffering is optional." Haruki Murakami