Hello all, as I have only had my 1990 300ZXTT for a couple of weeks now I have been experimenting with different Fuels. I.E. standard unleaded and Shell Optimax. Inside the fuel flap it's got a sticker with 98 RON on it which is why I have tried Optimax (bloody expensive) I was wondering if anyone could tell me what they usually fill up with and if it makes a difference?

Cheers

 

Glenn

 

P.S. My car has just developed an intermittent miss fire could this be down to the petrol???

Ok guys lets not get into one about petrol.

Those who use Optimax including myself know what difference it makes to the car and the engine. I can personally comapre this to super unleaded as I used this when I first got the car.

 

I think we have to just accept that unmark was told that super is just as good. We all know this is not the case as most of us have used both and the majority of us are still using optimax.

 

But when it comes to our views, I guess there is a fine line between advising and forcing :D .

Yeah Ukmark,

Just use cooking oil,I guarantee that will F**K your engine!!

F.T.

Originally posted by andrewwarren

Goin' to confuse the issue here as I have just looked under my flap ( oooh er missis ) and found a sticker saying 95 octane. :confused:

 

This must be because mine is a UK model. Do I presume that Uk and Imports are set up differently.

Mine doesn't really seem to benefit from super unleaded in any noticable way and I did use a full tank. Goin to fill up next with Optimax and see if we have any different results.:cool:

 

Well my car is UK too,It makes NO Differance If I use Shell Opticraps, super unleaded or 95 ron NONE AT ALL!

Just my opinion but I think the point is been missed here a bit.

 

When a car is run on a lower garde fuel than intended and asuming it is a stock motor misfiring is an unlikely result, it may be more prone to detonation and a lower performance but misfiring is most likely due to other reasons.

 

It could be argued that a poor spark that produces a misfire could be masked by the improvement in using a higher grade of fuel.

 

Having run a few zeds now I have had standard and mildly upgraded ones and have found that if all is essentially working well that standard unleaded is fine in Winter time (lower intake charge temp.) and super unleaded on every other tank ok in summer time temps.

 

The importantance of having the engine running right in the first place is the key I think.

 

Zappa

Iain, I think the reason why you are fine with normal unleaded is that you used a very responsible tuner who optimised your performance even at 95 RON :D

 

On another thing that's been mentioned, I really don't get the idea behind using higer octane petrol 'every other tank'. The benefits of high octane petrol are immediate and do not last - it's when the spark happens and then it's over. It won't help detonation if you had Super in there recently but not now.

 

Ukmark : no disrespect mate but it seems that the tuner gave you information which isn't correct - so why don't you just be grateful for the updated info instead of defending yourself. It's nothing to do with the place being clicky - it's just a forum for sharing information and people are trying to help but there isn't much point in seeking information if you're gonna ignore it.

 

Dave

I always used to use basic unleaded as using Super made no noticable difference to performance. However, after quite a lot of experimentation and detailed mpg monitoring I decided that using Optimax paid for itself in the extra mpg, therefore I now use it whenever possible.

 

Having said that, I have now noticed that the car never seems to det at all when using Optimax, although by being careless/stupid (way too much throttle at low revs) then I can make it det occasionally with standard unleaded.

Thought you would be interested in the following info I got from Shell. (Not getting at ukmark - just maybe the motorsport company who gave you duff info and should have been better informed.)

 

First an e-mail

Thank you for your recent e-mail concerning Shell Optimax

Shell Optimax has a minimum octane of 98 RON to which Shell guarantee, however, typically it is around 98.6.

 

It is not just the octane rating that differentiates Shell Optimax from other fuels. Shell Optimax is a unique highly refined new formulation which burns more cleanly to give you smooth power delivery. It is able to do this becuase:

 

* as the petrol with the highest octane rating in the UK it enables advanced modern design engines to work more efficiently thereby delivering more power

 

*it has the ability to remove performance sapping deposits left by other fuels from the airways of the engine

 

*it is free of the heavy constituents of petrol that leave dirty residue in you engine.

 

The combination of these effects means that the fuel and air flow smoothly and quickly to the engine, buring more effectively to give you increased performance and a quicker response.

 

For further information relating to your nearest stockist please do not hesitate to contact our Customer Service Centre on our free phone number 0800 731 8888

 

And a zipped Word doc which is their spec sheet.

 

This isn't independent but I would have thought Shell were usually quite reliable....

 

Cheers - Gio

Time to throw a few spanners in the works I think - well its better than drill bits :D

 

For a start, Super Unleaded has a lower calorific value than normal unleaded! This means it 'contains' less energy per unit, so in theory you'll get less power.

 

On another note, if you can use normal unleaded, use it! Using a higher RON than is needed will only coke your engine up faster - ie if you have a UK car don't use Super!

 

Looking at Gio's post above, Optimax is probably best to use. If you don't, then a UK stock car takes normal Unleaded, a stock jap car takes Super. If the car has been modified it basically comes down to where the car was tuned and what RON fuel was in the tank at the time.

 

HTH

 

CheerZ,

 

Andy

CHEERS gio now i am a belever ;)

I've got a uk zed and I use normal unleaded, is it worth using optimax? it sounds good

 

more confused now:confused:

I use optimax, I can feel the car responding a lot smoother,

 

my car smelt very eggy for the first month of using it like every time i put my foot down, that has stopped now though and its only occasionaly you get that cat smell.

 

I don't know if its due to the petrol or regular services but my mechanic said my engine looked like new,

Originally posted by andyduff

Time to throw a few spanners in the works I think - well its better than drill bits :D

 

For a start, Super Unleaded has a lower calorific value than normal unleaded! This means it 'contains' less energy per unit, so in theory you'll get less power.

 

CheerZ,

 

Andy

 

What a total load of utter unadultarated bullshit :D:D:D

So what you are in effect trying to say is that lower octane fuel has the potential to produce more power than Hi octane fuel

 

http://member.rivernet.com.au/btaylor/BMWText/technical/FuelOctane.html

worth a read.

Octane stopps detting ;) It doesn't give you any extra power - it is the fuel that gives the power.

 

CheerZ,

 

Andy

Higher octane fuel burns slower.

 

Detting is the fuel igniting before the piston reaches TDC. Higher octane fuel ignites later and so stops detonation (techy's - see my P.S. before you bite!).

 

I had it described to me as similar to the difference between lighter fluid and diesel. If you put lighter fluid in your hand and stick a match to it, it will flare and immediately go out - you will not burn yourself. If you do the same with diesel, you will not be able to light it. If you DID manage it, you wouldn't write for a month. Diesel has much greater energey but is harder to light.

 

Dave

 

P.S. before the techys say anything, I know that the mixture is always ignited before TDC but the simplification makes life easier to understand !

Well you learn something new every day. I dimly remembered from skool that octane did have something to do with how much energy was released when it burnt. So I surfed off to go and find the evidence that would prove you all wrong and start a fight (there's nothing finer than pouring unleaded on a roaring fire!).

 

But nope, I was wrong. Again :rolleyes:

 

Some links here

http://www.schoolscience.co.uk/content/5/chemistry/catalysis/catsch3pg9.html

http://www.stealth.fsnet.co.uk/page10.html

 

So octane is to do with anti-knock rather than power.

 

Cheers - Gio

:p Warren :p LMAO

Blimey, sorry if I have started something here guy's, but the general feeling seems to be that Optimax is OK in a 1990 ZXTT import then??? I must admit I put it in my other car and it does seem to run better.

 

 

Glenn

Originally posted by Hairsy

Iain, I think the reason why you are fine with normal unleaded is that you used a very responsible tuner who optimised your performance even at 95 RON :D

 

 

 

That's right Dave,been running 1 bar of boost and had this car set up by the best around:DStrange ehh Dave why I never ever never ever,have any problems with it;)

Originally posted by andyduff

Looking at Gio's post above, Optimax is probably best to use. If you don't, then a UK stock car takes normal Unleaded, a stock jap car takes Super.

Are you sure that a stock jap car needs super?

 

Mine had a 95RON sticker on the inside of the petrol flap and ran fine on unleaded for over 3 years until I upped the boost and changed to Optimax.

You're lucky, My Jap import has a red sticker with some gobbledegook in Japanese on it!!

 

So am I to take it that the Japanese ECU is calibated for 98 Octane then??

 

Paul

Probably closer to 100, but 98 is the best you are going to get in this country.

Yes Japan normal unleaded is the same as our Super Unleded. Some one must have changed the sticker.

Just to add in my penneth worth..

 

My import has lots of (and I really do mean lots!) 100RON stickers inside the fuel flap.. Someone in Japan obviously had a bit of a sticker fetish..

Maybe the previous Japanses owner of your car had a dumb wife who kept filling it up with 4 star :D

Go to the frst link to understand 100Oct.

 

http://www.gtr.co.uk/forum/upload/showthread.php?s=&threadid=6346&highlight=octane

 

If you have some serious time to devote to it then this thread will explain things more fully.

 

http://www.gtr.co.uk/forum/upload/showthread.php?s=&threadid=2480&highlight=octane

 

Most of you will know this, but for those who don't, I am 'Mycroft' on that forum.

 

Happy reading.:D