Safe to go to PAO?

My 1989 Acura Legend 2.7l V6 has about 250,000 km on it. I bought it used in 1992 with about 100,000km. Since then, it has had the 3 month 5,000km dino oil change. At about 150,000km I switched to full synthetics about the mid 90's. Don't know if they were PAOs or GroupIIIs. There doesn't appear to be any leaks now. Two years ago, it started getting syntec until I discovered the fiasco and just went back to dino. I now notice that the cost of filters for this engine has gone up to the point that it costs about the same to change twice with dino as it would with one change with Mobil SS with double the drain interval. What's better?