Land Rover recommends Premium Gasoline

[alzerom]

2004 Disco completely stock. I drove from Raleigh NC to Las Vegas Nevada in 40 hours on interstate 40 with speeds varying between 55 and 70, and returned a few days later in 40+ hours, 4667 miles, (yes a little too fast). I tried different grades of gasoline and noted the following:

At 55-70 on the interstate, Octane 87 - 89 - 91 appeared to make no difference, strong running and the mpg's stayed the same.

When I would stop and idle it would idle rough using the 87 and 89 Octane. It was quite noticeable. With 91 or greater octane the idle smoothed out. I repeated the testing proceedure several times on the 4667 mile trip, draining each tank to the bottom before switching octane ratings. I got the same results 3 times on the trip.

The price difference of the gasoline grades averaged $243 for the entire trip. This vehicle gets lousy gas mileage!

Question: would the use of the lower octane gas shorten the life of the engine?

 

[Disco Mike]

So, have you done your 6K along with the tune up and wires? How about gas additive and an induction cleaning.
Switch back and forth will drive your ECU crazy, stay with 91 Plus.

 

[whydahdvr]

In a recent drive from Boston, MA to Wilmington, DE I stayed with Premium the whole route. Judging from the prices I saw the difference per tank was only a few dollars between 89 and 91/93 Octane. The challenge for driving across the country is that in much of the central area there are dirtier vendors (their fuel tanks and supplies), more water (depending on your fuel stop), and different additives. Those will affect the fuel economy. Also, there is a gradual increase in elevation through the Great Divide and Colorado which impacts fuel economy, positive or negative depending on your direction of travel.
Land Rover's, like HMMVVE's or Hummer's, have certainly capabilities that negatively impact fuel economy but make them a more survivable vehicle. That's part of the trade-off.
For me on my recent trip by far the greatest negative impact to fuel economy was traffic. While I was able to use EZ Pass and not get stuck at toll booths the slow speeds, stop-and-go, and challenges of driving in heavy traffic had a significant impact on overall fuel economy. That and cargo load.
That's my bit to contribute. But it seems to do better with the higher octane and I imagine might get a bit better gas mileage to compensate for the higher per gallon price.

 

[alzerom]

I'm doing ALL maintenance on schedule. You are right it made the ECU go crazy and now I'm running 91 all the time.

Just before I left I used an additive for one tank to clean the fuel path. I used none on the trip. The plug wires are all original... so far.

Disco Mike has it right and I'll stay with the 91 octane, and it runs better. The Disco is certainly no highway cruiser. Mine runs great and the octane tests on the cross country just about proves what everyone is saying.

 

[pjvarc]

i drove from california to florida all the way down to key west.

on the west coast 91 all the way, south and east 93 and my disco love it, gaining a few extra miles too with 93.

i tried 87 and 89 as well and did not like the engine idle.

the high desert heat and southern humility was not a problem. i missed the mountains and deserts for now looking forward to the everglades for now,lol..

2003 disco 95k