I have done some research on this issue, but from what I can gather, there hasnt really been a particular answer to this question.

Is unleaded PLUS, grade 89 good to put in our 8's? I was curious if only PREMIUM can be used which is grade 91. Our book says grade 90 is recommended so I was wondering if 89 would be ok?

thanks for the help guys!

 

Some people can run 87-reg some can only run 91-prem. They recommend prem-gas but you can run reg if your engine does not detonate(Marble In A Can). You will hear some on here say only run Prem-gas but in my thirty eight years running Rotaries I have found that it all depends on the gas and engine tune. If you never want to worry about it run prem-gas always. If you run lower grade you have to listen to your engine and it will tell you if it can take it. You can also do the throttle body bypass it helps most people.

 

i ran 87 and never had an issue. try searching next time. you will literally uncover days of reading. somebody please close this thread before it gets out of hand

 

I run mid-grade gas in the winter and switch to premium in the summer because of the heat. You can get by with the bypass mod, I can't. It gets too cold here.