Back when Wal-Mart sold AC filters for less than $3 and Pennzoil for about a buck a quart, the change dino every 3 months like the manual says, sounded like a good idea. Well today they wanted over $8 for a 5 quart jug and I had paid over $5 for an L15436, we are talking almost $15 with tax. I am still reluctant to use the ST oil, and nothing else is that much cheaper than the PZ I have stuck with for 25 years. What is the longest time you would recommend keeping the same synthetic in my out of warranty 02 Cavalier Ecotec 4? I passed on the PZ for today. I did pick up a ST 3387A, PF 47 equivalent, for science. Cut it open, looks like about 96 sqin compared to the 112 sqin for a PF 47 a few years ago. The element is definitely too big to adapt in place of the PF 2244G element the Ecotec calls for. My outrage at paying 5-8 bucks for nothing but plastic end caps and media is not going away, and the price isn't dropping yet. The ST element also has less area than the smaller PF 2244G. Ideas?