By Bryan Crosby (Bcroz) on Tuesday, October 02, 2001 - 02:54 am: Edit

In a previous conversation I mentioned octane. My mechanic told me mid grade during the summer and regular during the colder months, someone else said nothing less than 90 octane anytime and the manual says 87 is ok. Anyone else got an opinion?

By Leslie N. Bright (Leslie) on Tuesday, October 02, 2001 - 03:07 am: Edit

What manual do you have?? (What year?)

I've got my spare copy here in my office (for my '99 SD), and on page 68 it says :
"Always use PREMIUM UNLEADED GASOLINE with a CLC or AKI octane rating of 90 or 92 (95 or 96 RON)."

Now, I'm an advocate of of not wasting money (yet I'm a Rover addict!!! ). When you pull up to a pump in different areas, the octane level can vary for the different grades.... I would go by the number instead of the name, ie. supreme, plus, silver, etc....

Here, mid-grade is 89 octane, and premium is 93 octane. On a computer-controlled vehicle, the system should be able to adjust to handle either of these grades. I wouldn't go down to regular, but would stick with one of these two.

I did use mid-grade myself, but here prices have come down such that I'm paying less for premium than I did for mid, and I'm wanting to avoid valve issues.

One thing to note: YOUR location. I don't know where you live, but some places (north of me, and in cities, but AFAIK not here in the rural south) reformulate their gasolines for winter, and it changes the performance of it. I was under the impression that it was for the worse, so the mechanic saying the lower in winter is okay sounds contradictory to me, but I don't 'know' about what's going on where you are.

L8R,

-L

By MTB on Tuesday, October 02, 2001 - 03:10 am: Edit

I am a TV junky and all the car show I have seen they all say use what is recomended by the MFG.
What most people were doing, they would use a 90+ octane when they should be using the car was calling for 87octane.
I only run 92+ and no problems for my baby 96Disco 65K

Michael B

By Bryan Crosby (Bcroz) on Tuesday, October 02, 2001 - 03:13 am: Edit

I'm in Michigan. The manual I have is for a 95 disco

By Leslie N. Bright (Leslie) on Tuesday, October 02, 2001 - 03:47 am: Edit

Michigan is a big area for reformulation, so it is a winter/summer thing for you. I still don't know about the specifics for your area, tho'... Anyway, you've got the 3.9 instead of the 4.0... (your manual is for the same year as for your truck, isn't it?); that's the difference. Yours is distributed, mine's not, etc. etc....

If it says 87 is okay, then run at least 87. I'd be tempted to run 89, but in your case I don't think I'd spend the extra to run premium.

IMHO, YMMV, driver on a closed course, yada yada yada, etc....


-L

By Robert Mann (Oldscout) on Tuesday, October 02, 2001 - 05:23 am: Edit

I thought that 96 and up have a knock sensor, So if you want to save some $$ and loose some power go 87. If you want full advance on your timing you will need to feed her something a little higher.

By Leslie N. Bright (Leslie) on Tuesday, October 02, 2001 - 05:31 am: Edit

Yes, the OBD-II does have a knock sensor, which is why the 89-93 fuel types are okay when the stated fuel range is 90-92.

Even if it can adjust timing to compensate for the shift in detonation from the octane shift, you're still risking the carbon-fouling... no knock-knock, but ya get plug-plug...

I'm a bit lucky, I guess... premium here in my neck of the woods is now at $1.42/gal.... so I'll run it instead of mid at $1.38....

-L

By Ron on Tuesday, October 02, 2001 - 06:00 am: Edit

oldscout,

Yes that is true BUT the premium tends to have more additives and we have seen a pretty much direct relationship between the dreaded valve job and using regular.

Ron

By ryan on Tuesday, October 02, 2001 - 10:15 am: Edit

I have a 94 Disco. Can I use mid-grade fuel(88 in my area) without messing things up. I add a fuel treatment thing every 3,000 miles.

By Leslie N. Bright (Leslie) on Tuesday, October 02, 2001 - 06:32 pm: Edit

Ryan,

I 'think' that you should be okay.

IMHO, YMMV, etc. etc....


-L