How important is it to use high octain gas in a 97 XJ8?

 

The XJ8 AJ26-27 family of engines is pretty forgiving with fuel requirements.
It's not necessary to use high octane fuels....also not good to use crap fuel either ;o)
These engines run happiest on mid octane fuel.
Trty to stay away fro ethanol laced fuel if you can.

Obviously in the US your octane levels are different to ours here in Australia.
I run 95 octane which is our mid octan fuel.
Yours would probably be the 92 octane?
It's more important to run a high strength fuel system cleaner
in the tank around every three months....dependant on useage.
This helps to keep fuel pumps and injectors clean.
My car has covered 200,000 and still singing ;o)

 

If you search my posts, I spoke about the fuel quite a bit in some of my old posts. I owned two gas stations, and was a fuel retailer for fifteen years. I think that I learned few things in those years.

Before you search, I'll give you the summary. I'll tell you what I do, and you can do as you please, of course.

1. I never pump lower grade than 91 (the highest available in SoCal)

2. I pump ONLY major brands (76, Mobil, Shell, Chevron, in no particular order) These are the majors in SoCal. In your state, there may be others.

3. I NEVER pump Costco, Arco, Valero, 7/11, Trifty, USA Gas, and other "non major" brands. Again,.....in your state they may be going by other names.

Every fifth tank, I pour Lucas fuel system cleaner in the tank. By doing this, I never have ANY issues with injectors, filters, fuel pumps, and such.

I was selling gasoline for 15 years, and attended numerous seminars, conventions, and workshops with two major brands (Mobil and 76). This is my experience, and this is what I do with my cars, bikes, and the plane.

 

Don't confuse 'high octane' with 'high quality'. One has nothing to do with the other.

You may want to do a search on the 'octane' and 'ethanol' subjects if you've got a few days to spare.

 

I use 89 chevron in my XJ8 with no issues, no pinging, no loss of that smooth 295 hp.

My XJR, on the the other hand runs 17 psi of boost, so I use 98 octane + water/meth injection. The xjr sees less miles.

 

This question has been flogged to death, most recently prior to this time on this thread and almost simultaneously on this thread.

You will never get agreement on this. I suggest you experiment with using regular (as I did to another poster in the second referenced thread) and see if you find the results satisfactory. I have, others have not.

What is clear is that you are unlikely to cause any permanent damage running these engines on 87 or 89 AKI octane fuel as opposed to the recommended 91 AKI.

I will also add that there are very few actual refiners of gasoline in the United States. Most so-called "off brands" come from the same refineries as the majors do. I've been using Costco, Wilco-Hess, Sheetz, etc., gasolines for years, and more frequently than I fill up with major brands, and have experienced zero problems.

 

If I ran 87 octane in my xjr i'm pretty sure I would have permenant damage

 

thanks everyone for your opinions. now I have to keep close tabs and determine if I want to take the risk or not. thanks