The pulley bolt on a 1990 Oldsmobile Regency 98 3.8L FI engine's tensioner is almost certainly a
right-hand thread. While there are exceptions in some very specialized applications, the vast majority of automotive bolts use right-hand threads. To loosen, you would turn it counter-clockwise.
However, always double-check visually before applying significant force. It's easy to strip a bolt. If you're unsure, carefully try turning it a small amount in both directions to confirm the correct direction.
