I know, I know, the question's be asked many many times whether premium is required. However, I'm not certain that my Disco needs premium:

1) The RAVE CD and manual list that some Disco's are NOT high compression and do not require premium.

2) Others have mentioned that their filler door is listed as premium (and most cars I've seen also label the gas gauge accordingly)---mine says 'unleaded only'...no mention of premium.

3) It's a '94 with a distributor, so the ECM shouldn't 'learn' the timing as usually mentioned. I've been running premium to see if the MPG goes up, but it had standard in it when I test drove it---and there was no knocking whatsoever.

Is there any way to tell if I have a standard-compression (8.35:1-ish) 3.9?

 

i know the old 3.5 came in high and low compression versions. you might be looking at that.

when it says unleaded only, that means dont use diesel.

 

lets say you put a full tank in. roughly 24 gallons? ill use the gas prices from where i am (near chicago)

(premium) 24 x 3.60 = $86.40
(regular) 24 x 3.40 = $81.6

when you really compare the benefits and peace of mind its not really worth buying regular, solihull didnt exactly pump out a bulletproof engine, and its just better for high mileage/older motors anyway imo

 

If you are in the United States you need Premium.

 

8.35 to 1 had about 160 Hp and none came to North Americato dealers.

 

If I understand it correctly, the problem with low grade gasoline is that the engine's valves cannot effectively clear the carbon on their down stroke, so eventually it will build up and a valve can snap/bend/break.

 

There are some older LR's with the 3.9 that have the low compression engine.
I guess the only way to know for sure would be to do a compression test. I dont know what the numbers would be for a high versus low compression engine, but if you tested all eight and then posted the numbers I am sure that somebody could tell you.
http://www.robisonservice.com/servic...er_advice1.asp

 

Every time is read this it reminds me of Consumer Report and we all know what they think.