wots the diff between super and optimax???

[mark_GSi]

does ne1 know the diff between super unleaded and optimax???

is there ne??

i know super is 98 octane, wots optimax??

using super on me GSi at the mo

[Nova-Boy]

optimax is shells own super fuel isn't it. It might be slightly higher octane or something than super.

Mike will know he swears by it.

[blingmachine]

optimax cleans your engine of carbon deposits and shit like that, higher octane means car go's faster

[rob.slader]

Both Super Unleaded and Optimax are rated at 98 octane where as normal unleaded is 95ron. The Optimax as Nova Boy says is Shells own brand of super unleaded. The Optimax has cleaning additives in that super unleaded doesn't. Optimax is better to use than the super unleaded because of this, plus it's slightly cheaper!

[Jim]

I use optimax, I was told to use it when I got the engine swap.

With my previous engine I tried Super Unleaded for a while and noticed no real change.

Jim

[scott5]

i think optimax is 99RON, makes the most difference on turbo cars cos u can run more boost without it detonating.

[rgv_stu]

optimax is 95 ron premium unleaded with octane booster and other additives

you will not find them advertise what ron it is because it goes off with age. when fresh its about 98/99ron but like i said they do not advertise its ron anywhere

[NovaNeil]

FACT!!!
Normal Unleaded 95RON
Super Unleaded (Found at such places as Texaco and Sainsburys Etc) 97RON
Optimax 98RON.
If you've got a GSi with an Octane plug, chances are it will say 93 on one side and 95 on the other. Go to Vauxhall and buy one with 95 and 98 on it. Then when you put Optimax in the tank change it so the Octane plug is on 98. You'll be able to feel the difference it makes then.
I think it slighty advances the timing or something.
I been told not to use the plug on a higher value than the fuel that you are using.

[Stuart]

ive never noticed a difference between using regular UL, Super UL and Opti (appart form the different dent in the wallet)

now for a proper difference find some REAL 4 star, last lot i bought was ?1.10 a litre, but hey it was ?5 of fun lol

yes there are places that are licensed to sell it, jsut youve gotta find it

[jatinder]

optimax is absoultley bolllocks i changed my plug over to 98 filled the tank three times didnt notice a thing apart from less money might work on newer cars didnt do a thing for mine

[NOVAS RULE]

it might just be a faulty ron plug

[Fester]

stu has made the most sense here

this sort of thing comes up all the time and MASSIVELY in depth on other boards i.e. impreza, skyline where the fuel used plays so much more a part of the engine performance and importantly reliability than it does in a Nova, unless of course the engine is of a spec. where it warrants you show discression with fuel choice

[mikeoxford]

i use optimax

my 2p worth

[Nova_Tek]

OK lads you've convinced me about optimax!

Just one question: can i use optimax on my 1.2 carb nova that can take both unleaded and the old 4 star?

Cheers!

[techie]

Youll need to adjust the timing to run optimax.

Optimax is 99ron. I used it in the Astra with good results, seem to pull alot better, which in theory it should as its got a higher octane rating. But then the Astra has knock sensors to control the ignition timing.

Havent tried it in he Nova yet, may consider it in the new engine though.

[Stuart]

in a brand spanking new engine it will make a difference (if you drop to regular unleaded for a tank ful you'd notice a dorp).

in an "old" engine it will take several tanks to even clear out the rubbish and then start to make such a mild difference.

the octane is a knock thing, the fuel itself more than likely has the same calorifica value as regular UL

[Dicko]

some more facts..
normal unleaded leaves the depo at around 95ron, by the time it gets in ur tank its about 94.2. super goes from 97 to 96.5 and optimax goes from 99ron to 98.7. unless you use a garage that doesnt do mnuch buiseness and the petrol is sitting in there tanks for weeks.
optimax contains cleaning additives, which for newer engines is good news, but for some oldf engines where carbon is the only thing sealing the valves properly its not.
however if uv ever used redex or similar this would cuase the same prob by removing carbon so swings n roundabouts.
iv used it on my 1.4sri engine and noticed the difference, and when the 1.6 16v was in my nova you could tell quite a difference, especially over 4k rpm

[Dicko]

1 last note...

if you dont boot your car all the time u will get more miles out of a tank o optimax than normal unleaded, however im not saying its cheaper as it costs more in the 1st place

[CP]

AFAIK the higher the RON
= the slower the rate of burn under compression
= less likelihood of pre-igniton
= allows engine to be set with more advance
= better combustion efficiency
= more power.

In reality a lot will depend on the actual circumstances of your engine. A newer higher tuned car running higher CR etc etc that can be set to run with higher RON fuel will benefit more than an older bog std lower CR engine with no adjustments made.

[mikeoxford]

= allows engine to be set with more advance.

hence why you have to set up the car with normal petrol in otherwise it wont run right in between. mines set up to optimax...... and i have marked the dizzy where the optimum for unleaded is (well, velos did)

[Nova-Boy]

does anyone know how many degrees exactly the igniton should be advanced from TDC to run unleaded or optimax? I think you need it 3 degrees more for unleaded when changing from 4 star.

[mikeoxford]

my two timing marks are about 2mm out if that helps?

[Stuart]

ignition advance varies from engine to engine, even the same model of engine.

theres no hard and fast way of "predicting" the ideal timing, and if it is set right its more or less a fluke lol