The filters that I've bought for several years from Deutsch and Mercedes looked to have plastic ends until you removed them at an oil change, that's when I noticed that the fibers of the end caps were deteriorating and getting soft.

Is this the filter your referring to? Because the STP's are showing no signs of deterioration at oil change. I don't know how well they are filtering, I need to do an oil sample to find out, but they look just as good when I take them out as when I put them in...

Dale