The book says 91.
The compression is 9:1 (not very high compared to my motorcycle at 14:1)
I would think that you could run a lower octane gas (89). All they sell here is 87,89,93. I don't mind putting in 93 (although it is $1.75 a gallon). I just don't want to use it if has no benefits. Many lower compression motorcycles will lose power if you run a gas with too high of an octane rating. What do y'all run in your trucks?????????

I love my new F150. It will stay stock for awhile, but I'm sure I'll find something to do to it. I already started by removing the lame "sport" decals.

Thanks,

Louis

 

I only run 87 in my truck. It says in the owners manual not to run anything but that. I do have a 98 with the 4.6L but I wouldn't think it should make any difference. I do hear a little ping every once in awhile but only when I'm towing and slowly ease on the accelerator. Otherwise else, it runs just fine. I do run only Amoco, or Mobil in my truck though. Mobil doesn't seem to idle as well as the Amoco though.

 

My book says 87 only for Y2K 5.4L,4X4 with auto and 3:55 LS.

 

87 octane...unless you have a chip (or have raised compression), any higher octane is a waste of money. FYI, higher octane does not refer to a better or "premium" kind of gas...is merely refers to the detonation qualities of the gas mixture; higher compression requires a higher octane rating to prevent predetonation (or "knocking").

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'99 F150 SC, 4x2, Oxford white, flareside, 5.4, 3.55 rearend,
bodyside mouldings, Snuglid hard tonneau, K&N dropin, airbox and frsh air mods.
Duraliner drop-in (gave up on the Penda Nascar). Gibson Supertruck. Ford 2-piece bra. Catch-All floor mats. Image tail light covers. B-Quiet sound dampener in rear of cab.
No door cracks yet at 10K!!!

 

Mine is a 2k 5.4 and my book also says only 87 octane. I use 93 now with the Superchip. It ran great before on 87.

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2000 F-150 XL,RC,LB,5.4,4R70W,3.55LS,
4-wheel disc/ABS,Chestnut/Parchment,
Ford bedliner & gas/wheel/spare locks,
3" cold air box modification,Superchip,
Dynomax ultra-flow welded 3" cat-back.

 

Hi LouisG,

With the factory programming, you'll want to run 87 octane in that vehicle, as that is what it is tuned for from the factory. Running premium gas with the factory programming is a waste, and won't get you any better mileage or performance in most of these late-model vehicles, because their fuel curves are set for the burn rate of lower-octane gas, and thus the engine will tend to "lay down" on 92+ octane.

The only time you want to use higher octane is if you are using a performance chip, raised the compression ratio as someone else mentioned, or if your engine exhibits detonation (spark kock, or "pinging") when using 87. If that happens, go up to 89, but you shouldn't have this problem.

Just like you mentioned about some motorcycles, the same thing can happen in these late-mdoel trucks when using premium, as they are simply not programmed (tuned) for it from the factory.

So as long as you don't get spark knock, and you're not using a performance chip, just stick to 87.

Good luck!

------------------
Mike Troyer
Performance Products, Inc.
National Distributor of Superchips
(540) 862-9515
Email: mtroyer@compuserve.com
Performance Products F150Online Superchip ordering system: F150Online Superchip Ordering System
First National F-150 Online Rally Info:https://www.f150online.com/rally2000/index.html

 

I also just use the 87. But it (seems) to idle slightly better at some times than others and it's probably due to my switching stations.....but no detonation yet and I pull an old (aka very heavy) popup trailer.

 

87 Octane...before the superchip...Only 93 with it.

No detonation or problems with 87 Octane.

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2000 F-150 XLT, 4x2, 5.4L Supercab, Superchip, Styleside, Black with silver two-tone, 3.55 rear, class III towing package with heavy duty cooling package, Heavy duty shocks, 4 wheel disk ABS, overhead console, sliding rear window, keyless entry, dark graphite interior, in dash CD, factory leather wrapped steering wheel, Pendaliner bedliner, K&N air filter, rubberized undercoating, cabin filtration system, Bugflector II, 5W-30 Mobil 1, engine build 10/4/99

 

87 Octane before the Superchip. 87 Octane with the Superchip.......Flip Chip that is.

 

if you are having a problem with engine ping, there is a octane adjust bar that most people dont know about on the right hand fenderwell, towards the rear or the engine compartment. It is hidden fairly well, and it is a gray connector with a blunt end. Just pull that connector apart and throw it in your glove box. A lot of people come in the shop and complain about their engine dies right after it is started and at the first couple of stop signs. The first question we ask is if the are using a higher grade fuel. 91 octane and higher will tend to cause this concern on cold startups. I have a superchip in my 2000 F150 5.4 and only run 87 oct. through it.

 

I have run my truck on all three octanes, and have noticed a difference in the mileage that I get per tank. If I run 87, I get about 30 less miles than if I run 89 or 90. However, if I run 92 or 93 octane, then I get about 20 to 30 less miles per tank. That is just my observations. If I can find 89 or 90 for the price of 87, I will fill with that. Right now with the price of gas being a $1.89 per gallon, I fill up with what ever is the cheapest at the time. Haven't had any problems running any gas from different stations.