LR3/Discovery 3 Fuel Grade Requirement

[WayneK9DI]

Hello,
First, I apologize for this double post, I'm visually impaired and work with a Service Animal. Obviously I'm not the driver, LOL, I'm in charge of RTFM activities. I didn't see this LR3 forum so I posted this same thread over in the Discovery forum and haven't figured out how to delete that one. So here goes.
My wife and I recently purchased a 2005 Land Rover LR3 SE ( marketed as a Discovery 3 outside of North America, IIRC ) with the Jaguar AJ41 petrol V8 engine fitted.
I was perusing the fine owners manual and came across the fuel requirements.
The manual states a minimum of 91 Octane rating.
My question is this, would a fuel octane rating of 87 be detrimental to operating our LR3? The reason for asking is that the 91 Octane rated fuel is $.40 per gallon more than the 87 Octane rated fuel.
Thank you all in advance for your kindly assistance with my question.

Wayne

 

[Houm_WA]

Yes

 

[WayneK9DI]

Care to elaborate?

 

[roverman]

I personally wouldn't worry too much about it. If it doesn't knock with 87 go ahead and use it. I used it for most of the 90,000 miles I put on mine. I can't recall hearing about any fuel related issues with these vehicles. I suppose you could make the argument that your throttle plate might get dirty sooner, but I only needed to clean mine once in the 9 years I had it. You might want to throw in a bottle of a good fuel injector tank additive now and then. I use 89 now with my LR4, just because really. Although it really is cheap 'insurance' to use premium, I don't think it's necessary.

 

[WayneK9DI]

Thank you. My wife and I will think on it and decide.

 

[safaridave]

I tried 87 on mine once and it did not perform as well, loss of power and it also used more petrol and I heard engine pinging. Went back to 91-93 better mpg, and performance.
Dave

 

[catman]

I think you will have to just try it and see what you think. The bottom line is that you will not harm anything running a few tanks through the system. If you feel it is not running adequately for your particluar use, just bump up the octane rating of the gas until it does.

The 2005 manual says that 91 RON (87 here in the US) may also be used. So it is not mandatory, just recommended. That would imply that the fuel economy and horsepower and torque ratings were based off that 95 RON (91 US) octane rating, using lower rated fuel may impact those numbers, but whether or not you notice probably depends on where you are and how you drive.

 

[safaridave]

I read that when I got my LR3, but my experience with 87 made me decide to use 91-93.
I can see how on the US LR3's with the Ford Ranger V6 engine 87 would work well.
Dave

 

[WayneK9DI]

Ours has the Jaguar V-8....

 

[catman]

I had a Saab that recommended premium (91 octane) years ago and always used 87 and never had an issue. That said, I had an 04 Discovery before our LR3 and RR and I was to scared to run anything but 93 in it because it was such a notoriously dirty engine. That habit has carried over and I have never used anything but 92 or 93 since, so I cannot say that running 87 in a LR3 would have zero impact, only that you will not damage the engine from doing so. If it runs poorly and knocks or pings, you should just move up a notch to 89 and if it continues, move to 91 (or higher).