3.9L recommended fuel and tank capacity? - Defender Source
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Old March 1st, 2004, 03:36 PM
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Payton Dobbs
95 Defender 90
Join Date: Oct 2003
Location: San Francisco, CA
Posts: 36
3.9L recommended fuel and tank capacity?

I always put 91 octane in my D90, but I was curious if this was necessary since I don't know for sure? Also, I've put up to 13.5 gallons in it, but what's the max?


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Old March 1st, 2004, 03:43 PM
rover4x4's Avatar
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1995 SW #487/500
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Location: The Old North State
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around 15 i think

Poor gas mileage gets you to the best places on earth
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Old March 1st, 2004, 03:48 PM
Eric Siepmann
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Eric W. Siepmann
1997 Defender 90 SW
Join Date: Dec 2003
Location: Chicago, IL, Cook
Posts: 883
The owners manual for 97 suggests 93.

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Old March 1st, 2004, 03:49 PM
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Mike Hippert
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94 D-90 Grinding Rover
Join Date: Sep 2003
Location: Manchester NH USA
Posts: 4,790
I'v put I think 14.6 gallons in one time, I always run 91 or higher in it, the owners manual says to put in 91 or higher and just as Phillip said the tank is 15 gallons, not quite big enough.
Don't forget to Search first then ask questions later! The loose nut behind the wheel
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Old March 1st, 2004, 05:37 PM
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Art Vigil
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Arthur Vigil
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Location: Hampshire, England
Posts: 716
The tank is 15.6 US gallons.
You don't necessarily need to run the highest octane you can buy.
Higher octane gasoline helps to keep your engine from pinging which can cause serious damage in a short amount of time.
Pinging usually only occurs when your engine is very hot and under full throttle.
The hotter your engine is, the more likely it is to ping.
I run higher octane gas in mine only because I have a supercharger which can cause the engine to operate at a higher temp than normal. I also use an octane boost before long road trips since I know the engine will be under a greater load.
In my last D90 ('95) I only ran the lowest octane gas available and never had any problems in 80K miles.
The octane level only prevents pinging, if you don't need it, spend your $ somewhere else. You can experiment with lower octane and depending on your vehicle & driving habits find a level that works for you. Lots of people think they're "treating" their engine when they put in high octane gas, I don't believe that to be the case, although I suppose peace of mind counts for something.
My .02
Arthur M Vigil
Colorado, USA Native
Former owner of:
'95 RRC - 3.9V8 Rimmer Supercharged!
'72 Series III 88" NADA Turner 2.25 petrol (Lovely Rita)
'95 RRC Brooklands/TWR Edition 3.9V8
'97 D90SW NAS #2426 - 3.9V8 Rimmer Supercharged!
'95 D90ST NAS#2620 - Original owner
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Old March 1st, 2004, 10:16 PM
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'94 D90 ST
Join Date: Jan 2004
Location: Manchester NH
Posts: 372
At higher altitudes you can sometimes get away with running lower octane fuel. But if you are at one of the coasts and near sealevel, you probably want to consider running super to prevent pinging.

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