Assuming you're asking about the Explorer; I'm the original owner, it's a '91 with the V6 (V8 not available first 2 years), mileage is 106k, regular maintenance, oil changes, never abused, off-roaded only gently a few times, etc. Only problem ever had was 3rd gear broke the first year, warranty item. 5-speed manual. The knocking under load or on very hot days with regular gas has been evident since the car was new. With high-octane fuel, it never knocks.

It's the "family beater" now, although 106k is pretty low mileage for a 16+ year old car, and it's in fair shape for it's age. Only worth about $1000 on a good day, I could never replace it for that amount of money.

I'm not complaining about what amounts to only about eight dollars a month more to buy premium gas for 2 of our cars. With the V6 in the Explorer, it's always gotten an average of 20- 25 mpg...better than the RX-8! Excellent for an SUV of this size. My daughter will be learning to drive on it soon.

 

I have been running 89 octane since new, no problems, hesitations, pings, or knocks.

 

"Why Premium Gas?" you ask. I have run only 93 octane for close to 60K miles in my 04 6MT so I can't comment on lower octane performance. But I can say if you're paying $40 for a tank of 87 or 89, what's the difference in $41.50 for premium? I don't baby this car and get consistant 20 mpg city/hwy and it has never missed a beat since day 1. It's like 95 degrees here just about every day this time of year and i've never heard a ping or knock.

That is why premium gas IMO. To each his own.

 

10:1 compression

 

i used 93 for about 25k miles, then i mixed my own gas which was about 97 octane high power mix. then I took a road trip and wanted a cheap alternative, so I used regular.

whatever works for you.

 

20k miles a year / ~21mpg = ~ 953 gal of gas...

953 gal of gas x .20 cents a gallon = 190 bucks a year..

if it runs the same, you choose... for a street driven na car the choice is simple for me..

now track days.. put in the good stuff..

beers