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Shell Optimax


mercenary
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OK I'll stick my neck out again and risk being shot down in flames :D

Back in the old days lead was added to petrol as an "anti-knock" and the amount of lead added increased the Octane rating of the fuel. The higher the Octane rating the slower and more controlled is the burn of the fuel, "burn not bang". This allowed higher compression ratios and more advance of the ignition without inducing "pinking" (pre-ingition) and over heating, hence more power. Obvoiusly lead has now gone and petrol companies are using other additives to increase the Octane rating of the fuel.

However the compression ratio of the engine is fixed and the ECU is programmed for SUL, so using Optimax will not give more power but it will reduce your bank balance. Having said all that if you have a blower and the ECU has been re-mapped it probably will be better.

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I didn't see an altezza owner input so far about optimax :whistling: :P

I tried it a week ago for the first time and the engine was a lot smoother, but I am not sure about the performance claim!

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The only sure way of knowing if Optimax does give a power increase would be to dyno the same car, with the same setup, on the same dyno, using bog standard 97 RON versus Optimax

I'll volunteer if Shell is willing to pay for it! :winky:

But I'll bet they don't :blink:

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  • 2 weeks later...

If like me you have an imported motor (preludevtec) it needs at least 98ron which of course you cannot get, but when u do speed/cooler engine/ and better gasses................imports only, didnt make any difference to the Lex!

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Here is a response from one of the members who PM'd me with a response to this post. He happens to be employed by the very same multinational who happen to produce the Optimax brand but I think his reply is very objective:

"There are two octane numbers RON and MON.

The RON of Optimax is 98 and the RON of normal mogas is 95.

There is then MON which for Optimax is 86 and normal mogas 85.

The octane is a measure of how efficent the burning is in the engine. A high octane fuel will completely combust at the same time as the spark plug activates. This gives maximum force on the piston forcing it down. A low octane fuel will burn before the spark plug ignites (this can lead to back firing) or will combust for a short time after the spark plug activates meaning that the piston is not pushed down with maximum force and a loss of power.

RON is measured by the engine at high revs and is generally a measure of how well the fuel helps the engine accelerate. MON is measured at more steady revs and is a measure of how well the fuel helps the engine cruise.

Optimax will give more efficent combustion untilising more of the power of the fuel in making the car go.

Roughly speaking mixing 50:50 98.0 octane and 95.0 octane gives 96.6 RON so almost but not quite linear".

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Here is a response from one of the members who PM'd me with a response to this post. He happens to be employed by the very same multinational who happen to produce the Optimax brand but I think his reply is very objective:

"There are two octane numbers RON and MON.

The RON of Optimax is 98 and the RON of normal mogas is 95.

There is then MON which for Optimax is 86 and normal mogas 85.

The octane is a measure of how efficent the burning is in the engine. A high octane fuel will completely combust at the same time as the spark plug activates. This gives maximum force on the piston forcing it down. A low octane fuel will burn before the spark plug ignites (this can lead to back firing) or will combust for a short time after the spark plug activates meaning that the piston is not pushed down with maximum force and a loss of power.

RON is measured by the engine at high revs and is generally a measure of how well the fuel helps the engine accelerate. MON is measured at more steady revs and is a measure of how well the fuel helps the engine cruise.

Optimax will give more efficent combustion untilising more of the power of the fuel in making the car go.

Roughly speaking mixing 50:50 98.0 octane and 95.0 octane gives 96.6 RON so almost but not quite linear".

Sorry but don't buy that.

1/ If the " fuel will completely combust at the same time as the spark plug activates" it will be pushing against the piston on it's way up! The spark is timed BTDC (Before Top Dead Centre). The more revs you have on the more the ignition timing is advanced BTDC

2/ If the piston is at TDC the force is completely down through the con rod into the big end and mains. So does nothing to the piston apart from putting a "hammer blow" on an immovable object.

3/ To produce max torque (hence power) you need the max burn to be when the crank is at 90 degrees (ideally) force x radius e.g. half way down the ignition stroke.

So all in all I would say b*****cks to that.

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  • 2 weeks later...

I've been watching this closely - 2 fills and 550 miles later

1) 26 mpg (90% motorway, balls to the wall)

2) 29 mpg (70% motorway, 80-85 mph)

This is 1.0 - 1.5% better mpg than I was getting with Sainsbo's 97 Super

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I've got a Honda Accord 2.0 Si as a Daily driver (to work and back). It's a 1989 JDM car, that has no remapped ECU or anything whatsoever, but when filled up with Optimax, BP Ultimate, or even the new Tesco SUL 99RON the car runs smooth as it ever has done on SUL. The same with the Aristo, for some reason the engine just does NOT feel as "revvy" as when I'm running a higher octane fuel as opposed to running normal SUL.

I guess it's mostly for use in JDM cars as opposed to UK cars.

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Dosnt that % fall within the realm of allowed variability.

Really need to do a lot more fills and trips and average it out. I know that one tank full I can do 300 miles, the next just 200. Depends what kind of a mood im in that week ;)

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I'm sorry my reply is unsatisfactory for neil.macdonald8. It is verbatim from the technologist working on the unit that produces and blends Shell fuel and optimax. I trust his explanation because I know him and the operators on the plant.

Yes I do work for Shell, and yes we do make a vast amount of money, sadly not as much as we collect for the governement, but we do make money, that is why we are in business and it is why we are good at what we do.

From my own humble experience having driven my IS200 for 5 and a half years I have recorded 52K miles on Shell at 31.6mpg, 10K on Safeways finest at 31mpg, 9K on Sainsbury at 32.8mpg. The best has been BP 33.82 mpg but only for 653 miles. Over 78K miles the average is 32mpg, but I try to be smooth and fairly gentle with the car so Optimax is not for me. ( I'd post the spreadsheet but not sure how)

Bottom line is there is a choice out there, though most of the fuel is produced by a few major suppliers, this is well known and is accepted practice. From my office window I see Asda, Texaco, BP Safeways tankers filling up at the terminal. BUT, you only get the Shell additives on a Shell forecourt. I buy most of my fuel from a company that has it's primary business of petrochemicals. I buy bread and beans from a supermarket.

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so what is the difference between tesco petrol and the stuff you get at the shell/bp station?

What do the additives do? Im talking about the normal 95ron stuff.

If Optimax does indeed offer any benefits I cant say ive seen them. Or the difference is so tiny only a lab test can prove it so for me the normal stuff is good enough. I also get clubcard points and the company pays for my petrol, its like free shopping :D

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so what is the difference between tesco petrol and the stuff you get at the shell/bp station?

What do the additives do? Im talking about the normal 95ron stuff.

If Optimax does indeed offer any benefits I cant say ive seen them. Or the difference is so tiny only a lab test can prove it so for me the normal stuff is good enough. I also get clubcard points and the company pays for my petrol, its like free shopping :D

Shell and BP spend a fortune on research to get a package of additives that clean the deposits from your engine, allow the fuel to burn cleaner, reduce emissions etc. Tesco et al buy the base product from anyone who has a surplus of the base product and sell it often as a loss leader.

With my driving style on the roads I travel Optimax confers no benefits, if you acelerate hard, drive on the limit, Optimax ( or BP ultimate) will be your fuel of choice.

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Again I will put myself up for correction :duh:

My understanding, and has been for years, is that a higher octane fuel has a slower, more controlled "burn" and hence the burning fuel is still expanding while the piston travels downwards where it can exert maximum torque on the crankshaft. Lower octane fuels "explode" rather than "burn" and this results in pre-ignition (pinking) and hotter running in the combustion chamber.

What I am saying is that a higher octane fuel will not give any more power unless other parameters are changed such as ignition timing (re-map rather than re-set ECU) and compression ratio which is obviously fixed.

I have no doubt that the additives can indeed help with upper cylinder lubrication and with keeping valve seats clean etc etc.

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Motorway is rarely clear enough to do anything over 60 and the country roads are too narrow.

The only time Ive ever pushed my car is on the M6 toll where I had my foot to the floor and the rev limiter kept me from reaching anything over 140mph :whistling:

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Motorway is rarely clear enough to do anything over 60 and the country roads are too narrow.

The only time Ive ever pushed my car is on the M6 toll where I had my foot to the floor and the rev limiter kept me from reaching anything over 140mph  :whistling:

140 in a standard N/A IS200SE? Surely not!

Do you have a blower or S/C you're keeping secret? :winky:

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Motorway is rarely clear enough to do anything over 60 and the country roads are too narrow.

The only time Ive ever pushed my car is on the M6 toll where I had my foot to the floor and the rev limiter kept me from reaching anything over 140mph  :whistling:

140 in a standard N/A IS200SE? Surely not!

Do you have a blower or S/C you're keeping secret? :winky:

Ahhhhh the M6 Toll road :) :D :D ......i too have done 140 in mine, again on the toll road :whistling:

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  • 9 months later...

Brilliant review thorough and good research is commendable mate!

I have Optimax and I must admit I did feel that the car felt smoother and was more responsive, BUT I think this may be down to the Psychological factor of reading all the bollocks in magazine and reviews and when you do decide to fill up you think that the car is faster and smoother.

I have no doubts that Optimax does clean your engine but if I was to have my IS200 filled up with various petrols then told to drive it without knowing what petrol was in the tank I would not notice the difference.

BP Ultimate is the same it felt no different to tesco Unleaded to be honest and I ganied no mileage difference, howevr i do agree that on various tank fill ups I have noticed that the mileage does range about 100 miles each tank full but all this depends on how you drive etc.

so my conclusion is all the petrols are the same some just cost more!

:winky:

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