I use regular 87 octane with no problems. Also run it in my R27 with no problems and it has been on a regular diet of 87 for a long time. I would be hesitant to use a high grade these days. Was filling up a year or so back, when the gas supply truck was unloading. The drive came over, we were talking cycles. I asked if they sold much high octane these days. He gave a weak little smile and said he had done nothing more than a slight top off ever now and again to the high octane tanks for at least a year. He said that demand for premium was way down. So, I am thinking if this gas has been sitting in there for who knows how long.....what kinds of problems, gunk, water condensation...is it collecting in there. Maybe none but on the other hand........................