Amen brother!! I made the mistake once several years ago of wiping the cob webs off of the premium fuel pump handle at a no name gas station in a name no name town while on a 'froadin' trip and my truck spit and spuddered and bucked and yawed...but she got us home.
Topped of with Shell premium and she ran great.
Lesson learned, 87 is ok once in a blue moon or in a emergency but not as a steady diet.

 

All of my state has 10% ethanol in the fuels no matter what grade

87 runs poorly in my disco as well but she runs tip top with 89

 

Whatever works for you man.
I ran 89 for a few tanks and noticed a difference.
Right now I am using Costco premium, my truck idles kinda rough when hot but runs fine down the road, cant tell a difference in mpg.
I want to switch back to Shell but damn the $.06 per gal savings is hard to pass up.

 

I wish Amoco or BP would be in my area..but no

 

Back to my original question... premium or Super premium (which I've been using)???

 

The words Premium and Super premium don't mean anything. You have to go by the octane, 87,88,89,90 ect ect.

 

91 as well. So which is it? Different owners are using different grades. Which one is most highly recommended and best for the engine long term? Would that be 91 since its the highest?

 

Whatever you can afford. 91 is better but 89 and 90 are good.

 

Have you looked in your owners manual at the manufactures recommended fuel grade? Also, octane rating has no affect on fuel economy. If you think you got different fuel economy with a different octane, and think it was because if the octane rating, you are blowing smoke.

 

I can shed some light on this subject, and that is just don't! Only use 91+ octane, all these engines lack an egr system. The lower the octane, the higher the cylinder temp, causing the oil to burn in the heads. Eventually all the sludge in the heads will block off the return passages and starve the engine for oil and it will do something crazy like throw a rod (that is what my truck did before I got it). Not to mention when you really think about it the cost difference is very little compared to a new engine. My wife's Mercedes is the same way and it has two knock sensors, yet it is only rated for premium fuel.