I too had trouble using PENNZOIL air cooled. Less than 5 gallons I had stuck rings on two different motors. TAURUS 52, 3W-106. So It's back to BEL-RAY MC-1 @ 50:1 for me! Been using that brand for many, many years with no problems.. I don't know why I switched in the first place. Maybe to try something new I suppose. I also noticed a power loss with PENNZOIL flying the TAURUS. Hard to tell on the 106 That motor rocks at half throttle. O well, Live and learn.