I only got my TJ 2002 in April/May, with only 13642km on the clock. Without doing too much research into the topic I decided to run Premium unleaded in the car thinking that the engine is still relatievely new (only just broken in really) and i wanted to run it with the higher octane/ better quality fuel.

Can anyone tell me if there is any scientific evidence which supports or goes against my idea, what effect does each fuel have on the engine performance and wear, does it effect fuel efficiency/economy? Any info would be of great help.

p.s the car is completely stock, Iam aware octane level in fuel is imp with particular mods (unichip). Have only had regular unleaded in the car for the first tank of fuel, ever since then have put premium in it.

There is a few people who swear by premium increasing fuel econ.

It doesn't! It contains the same amount of energy per gram as 91 ron fuel and the extra pre det protection cant increase HP or fuel econ without being tuned for it.

Run whatever the hand book says to. (91ron)

PS: your ecu cannot learn or ever tell what its got in it because there is no knock sensor.

3rd gen magnas have no K.S so run the factory recommendation unless you have an ECU or A/F controller....

is there an echo in here? :P

As far as I know 3rd gens have no KS so I also believe that you should just run what is recommended :D :bowrofl: :lurk:

yes there is an echo :P

no knock sensor = no premium.

WSDburbleburbleburblevroom

dont knw if its been mentioned but the 3rd gen doesn't have a knock sensor so just run 91ron fuel

I have ran Optimax since new. So have I been wasting my time then?:redface: :confused:

i dunno maybe its just a placebo but when i run on premium throttle is smoother and more responsive.

fordy, ive never read anywhere saying it actualy helps keep the fuel system clean or reduce matenence, so yer u have been wasting ur time. specialy in a bog stock NA big 6

On the occasions i put a tank of Optimax in mine it seems to gothat bit harder.

Well that sux :nuts: :angry: :angry: :nuts:

i do a lot of country driving and i find i do get an improvement in fuel economy using premium in efi cars, even ones without knock sensors (eg VN commodore), i know theres supposed to be no difference but i find that on premium i get further per tank and the extra is enough to justify the cost of premium. there is also a very slight improvement in performance on premium, i doubt there would be much fuel economy difference city driving on premium.

Do you guys read the prior post(s) before repeating what's already been said?

there has been alot of double postings, do you people read before you post?



:stoopid:

i do a lot of country driving and i find i do get an improvement in fuel economy using premium in efi cars, even ones without knock sensors (eg VN commodore), i know theres supposed to be no difference but i find that on premium i get further per tank and the extra is enough to justify the cost of premium. there is also a very slight improvement in performance on premium, i doubt there would be much fuel economy difference city driving on premium.
i bet if i filled it up and told you it was 400ron you would notice it went better, when i actualy put diesel in :P

it doesn't make a difference!

ive read so so much about this....


While many people claim that their car runs better on premium, this costly fuel is really only needed in a few circumstances. However, when it is needed, it must be used to spare your engine from costly damage. On the other hand, if you burn premium when your car doesn’t need it, the damage won’t be to your engine but only to your pocketbook.


If you enjoy using premium because you think it makes your car “happy,” then go right ahead and use it. President Bush has asked Americans to spend money to support the economy, so you can view it as your small patriotic contribution. And if you own stock in an oil company, so much the better. Using fuel with a higher AKI than needed will in no way harm an engine. Also, your engine won’t get “a taste” for the good stuff and rebel against you if you fall on hard times and have to use cheap gas.

Well i am a beliver in premium!!!!!!
Yes there is one here. I have had my car for 18 months now, for the first 6 months i used regular unleaded fuel, then one day i gave the premium unleaded fuel a try. I certainly noticed a distinctive difference in the way the car drives, felt smoother and more powerful too me. In terms of fuel economy for me it is slightly better but not too much. I feel that by feeding my car better fuel, the engine will be healthier over the long term, that goes with everything really. I wont use regular unleaded in my car again. As soon as i get my car on a dyno tune again i will have it dyno tuned for BP ultimate 98ron then that will be only fuel i use then
Cheers
Paul

I was told by a mechanic to run premium through the tank once out of every 3 tanks. Apparently it helps the fuel system to clean. Dunno if its true bit it can't hurt

preimium dude she need premium

bah :P we have patriots :P

its hard to argue when its really only like 3 bucks a tank

Thanks for the info guys. Like mentioned in a prior post, it really only equates to a few extra dollars a tank, and then this can be reduced by fuel vouchers. I think I will still use premium unless someone has any real evidence/experience to convince me other wise.....

yeah. i've bin told premium is a good "flush" after a few tanks of regular unleaded. maybe that's y ppl have noticed a difference because once everything is flushed with the premium, you'll notice a small increase in performance and/or fuel economy cause everything is running like it should. :nuts: could b cause im half asleep too

i bet if i filled it up and told you it was 400ron you would notice it went better, when i actualy put diesel in :P

it doesn't make a difference!

As a habit i reset the tripmeter evertime i refill a car. I have driven a full tank to empty many times on both unleaded and pulp. in most efi cars i have owned everytime i use pulp i get further out of a tank. In my old VN V6 auto wagon the difference was over 100km per tank further on pulp with no other changes. VN's don't have knock sensors. Yet in a auto VL turbo i had there was no difference in economy per tank on pulp just performance. VL turbo's do have knock sensors.

Turbo_charade have u ever tested the difference in milage per tank yourself? or are u just going on what other people tell u?

Power wise there isn't an apparent difference between the fuels. The higher RON allows greater resistance to pinging / knocking. That's why people get them tuned to those fuels, so they can advance timing or use higher compression or greater boost, not to increase power because they think the fuel has more power.

It is however possible to get greater economy and idling could be smoother. I saw an increase in economy from Shell Optimax which was worth 50km's in city / suburb driving but 50km's further isn't worth shelling out another 8 cents per litre.

http://www.epinions.com/content_2346164356

its all just unrelated :rant:

someone try find something to back it up other than dodgy trip meter read outs

I consistently got 60-70Km per tank extra using Shell Optimax than if I use regular uinleaded from 7/11. That was driving to and from work for 2 weeks using 7/11 fuel, then the following 2 weeks using Optimax. I think the difference in price to fill up per tank worked out to be something like 4-5 dollars.

echo? wot echo? i dont hear no echo :)

sigh.... physics...physics...physics....no knock sensor....= engine cant change timings to make use of higher RON... timing will remain as set at factory.... which is for 91 RON no?

unless u get timings changed to suit for higher ron (tuned for premium)

Ask mitsu design office ... they will tell u.

higher RON wont hurt... but neither will fluffy dice and magnetic armbands....

Optimax etc have 'u beaut futuristic' additives...cleaners etc... which can be helpful once in while ....
And Optimax all the time wont hurt....if u want it do it.

But i reckon my car goes quicker and is more powerful on normal unleaded.... (probably coz im more willing to use heavier foot and get crap economy coz the fuel is that bit cheaper :P)

echo? wot echo? i dont hear no echo :)

(the shame of it... im agreeing with a charade driver....argh
:confused: )

WSDpedalgoesdown,wheelsgoround,gogoesforward.

It's a 64Km round trip from my home to work to back home again and I can guarantee you that Optimax definately gives me around an extra 60-70Km per tank than the standard 7/11 unleaded I compared it against. I know for a fact 'cause I used my trip meter and I also had to fill up a day earlier if I used standard unleaded.

Probably 2/3 of that is constant 100Km freeway driving and about a 1/3 is start/stop across the Westgate and down to Power Street and across Swan Street to Batman Ave (if anyone knows Melbourne!!!).

echo? wot echo? i dont hear no echo :)

sigh.... physics...physics...physics....no knock sensor....= engine cant change timings to make use of higher RON... timing will remain as set at factory.... which is for 91 RON no?

unless u get timings changed to suit for higher ron (tuned for premium)

Ask mitsu design office ... they will tell u.

higher RON wont hurt... but neither will fluffy dice and magnetic armbands....

Optimax etc have 'u beaut futuristic' additives...cleaners etc... which can be helpful once in while ....
And Optimax all the time wont hurt....if u want it do it.

But i reckon my car goes quicker and is more powerful on normal unleaded.... (probably coz im more willing to use heavier foot and get crap economy coz the fuel is that bit cheaper :P)

echo? wot echo? i dont hear no echo :)

(the shame of it... im agreeing with a charade driver....argh
:confused: )

WSDpedalgoesdown,wheelsgoround,gogoesforward.
i like this man! ITS PURELY PLACEBO!

However, the second gen's did have a knock sensor...

I did notice a slight difference in power, and economy, but it wasn't enough to justify the extra cost. Espeically when I was gettin in some cases 330km to a tank...