87 Unleaded or 93 Premium

[jvazquez53]

After filling my tank about three times and keeping MPG record, the MPG was lousy. Today I filled up with premium 93 octane. Reason for this, a lot of people use here premium and they claim better mileage. We'll see.

 

[ajax1]

I run 85 gets same mileage

 

[Timpanogos Slim]

85. tractor motor.

unless you have forced induction or are otherwise running advanced timing.

 

[jvazquez53]

85. tractor motor.

unless you have forced induction or are otherwise running advanced timing.

8 MPG is really bad!

 

[Michael Hanson]

Hi, When's the last time you ran the valves ? Mike

 

[92LXAZ]

Everything I've heard is it doesn't make a difference (have not tried myself, and won't). Even if it does in some cases it's most likely a wash at best at the bottom line. Any improved mileage is negated by the increased $$ spent for premium. Plus with a 20+ year old 4.0 liter motor premium fuel wouldn't do anything in my opinion. 8 mpg is pretty bad but have you tried all other tune up options? Hope you find improvement somehow though.

 

[Timpanogos Slim]

8 MPG is really bad!

Plus since it's a 3fe it's slow!

i'd try the obvious tune-up stuff first.

lemme clarify - higher octane is not really "better" gas.

It's gas that ignites slower.

This means that the timing can be advanced without as much risk of knocking.

My volkswagen with it's itty bitty turbo 2.0 has more horsepower and more torque than my 1fz-fe but _requires_ 91 octane minimum and says so right on the filler door. You can put 85 in it and it will run but it will retard the timing, run worse, and the miles per dollar turns out to be sixes.

Your truck has a relatively low compression engine. you don't need premium. You need to figure out what is wrong with your engine.

 

[scrowley]

They sell 85 ocatane..??? Never seen that at the pump.

 

[livinoffroad]

Plus since it's a 3fe it's slow!

lemme clarify - higher octane is not really "better" gas.

It's gas that ignites slower.

This means that the timing can be advanced without as much risk of knocking.

My volkswagen with it's itty bitty turbo 2.0 has more horsepower and more torque than my 1fz-fe but _requires_ 91 octane minimum and says so right on the filler door. You can put 85 in it and it will run but it will retard the timing, run worse, and the miles per dollar turns out to be sixes.

Your truck has a relatively low compression engine. you don't need premium. You need to figure out what is wrong with your engine.

Exactly Slim !!
These beasts were designed to wander the third world, filled with crappy gas, infrequent maintenance, and perennially dusty conditions. How many owners know there's a mini pre-filter on your air filter can, which is serviceable, without having to open the main filter can. Some of us refer to it as the "tuna can", as it's about that big.
Anyway, low compression is part of the design of the 1fzfe, in order that low octane fuel can be used. I've used 85 here in Idaho for 8 yrs, and never experienced detonation (pre-ignition). Since high octane ignites slower, or completes burning later, more of the unburned hydrocarbons leave the cylinder, burn in the cat, and result in higher cat temps. HTH

 

[jtwopark]

check for vacuum leaks and do a tune up first. I have a 93 and was getting around 6-7 mpg. the dealer wanted something close to $7000 to service my LC back in feb of this year. Since then, I have been slowly replacing all the vacuum hoses and the intake hose...spark plugs, wires, new clamps here and there,.....gaskets, o-rings....it now back up to around 10-12 mpg....i know we have different engines...but a engine is a engine....so hope this helps some.!

 

[jvazquez53]

Hi, When's the last time you ran the valves ? Mike

I don't recall. What I'll next do is a full tune up. Plugs, timing, finish desmog, air cleaner.

 

[hammerheadfistpunch]

Running premium fuels in the 3f or 1fz should lower your fuel economy, since it will burn less completely (i.e. harder to ignite) not to mention that since all fuel in the US is E10 at least (thanks Obama) your real world octane on 85 is closer to 91 anyway. We had a supercharged 454 vortech that (pre e10) ran much better in the cold with 85 than 91 and post e10 ran 100% in all but the hottest towing loads with e10 85.

 

[jvazquez53]

check for vacuum leaks and do a tune up first. I have a 93 and was getting around 6-7 mpg. the dealer wanted something close to $7000 to service my LC back in feb of this year. Since then, I have been slowly replacing all the vacuum hoses and the intake hose...spark plugs, wires, new clamps here and there,.....gaskets, o-rings....it now back up to around 10-12 mpg....i know we have different engines...but a engine is a engine....so hope this helps some.!

Thanks! I'll do this, as for vacuum hoses, the truck don't have many, it's being desmoged. Gaskets OK, I'll check the timing...

 

[jvazquez53]

Running premium fuels in the 3f or 1fz should lower your fuel economy, since it will burn less completely (i.e. harder to ignite) not to mention that since all fuel in the US is E10 at least (thanks Obama) your real world octane on 85 is closer to 91 anyway. We had a supercharged 454 vortech that (pre e10) ran much better in the cold with 85 than 91 and post e10 ran 100% in all but the hottest towing loads with e10 85.

Here we can get 93-96 up to 100 (100,pricey!) I just filled the truck with 93.

 

[Timpanogos Slim]

They sell 85 ocatane..??? Never seen that at the pump.

high altitude. Where the 'premium' is 91 octane.

There are ways for me to acquire race gas and other specialty fuels, but 85 is not uncommon in colorado, utah, etc - while 93 octane is basically not something i can just pull up to a pump and put in my car here.

 

[hammerheadfistpunch]

high altitude. Where the 'premium' is 91 octane.

There are ways for me to acquire race gas and other specialty fuels, but 85 is not uncommon in colorado, utah, etc - while 93 octane is basically not something i can just pull up to a pump and put in my car here.

Yup, Utah 91 is the best you can get, which sucks for increasing boost on a turbo car like my old forester, turbo's don't know its 5000 feet out there, they just pressurize to wastegate pressure. fortunatly 91 is more like 94-96 because of E10. We can get race gas at the pump here...but why?

 

[Timpanogos Slim]

Yup, Utah 91 is the best you can get, which sucks for increasing boost on a turbo car like my old forester, turbo's don't know its 5000 feet out there, they just pressurize to wastegate pressure. fortunatly 91 is more like 94-96 because of E10. We can get race gas at the pump here...but why?

the answer is water/meth injection. for forced induction engines anyway.

 

[08720]

8 MPG is really bad!

It looks like you are driving through water. Try driving on the road some and see what happens. Thats the best I can do. I hope you figure it out.

 

[mmeister13]

lemme clarify - higher octane is not really "better" gas.

It's gas that ignites slower.

This means that the timing can be advanced without as much risk of knocking.

Just to clarify higher octane fuel doesn't "ignite slower". It just means that it requires more energy to start the combustion process and reducing the likelihood of knocking not improve fuel economy.

I had some bad knocking with mine while I was using 87 and I knew that shouldn't be the case so I did all the easy fixes that everyone suggested and it seemed to help.

 

[Delancy]

lemme clarify - higher octane is not really "better" gas.

While that may be true, based on the chemical composition, higher octane in some states, may be the only choice that isn't ethanol blended at stations that don't advertise "100% Gas".

The leading retailer in the metro area I reside blends the lesser two octane ratings with up to 10% ethanol, the middle grade being a combination of the highest and lowest octane ratings.

We could debate the merits of ethanol all day, but believe its been found to be less efficient in earlier engines, pre-2004 is what I recall, and potentially harmful. For that reason, especially with summer blends, I choose the higher octanes.





Oddly enough, they had no 100% gas at this stop.