I have a wrx (import) what petrol am i suppose to use, i have been useing normall unleaded and it gives me more millage then the super unleaded from bp?

 

If it is a standard import - ie no ECU mods or remaps - then you are killing your engine with straight UL! The car will be timed to run on 100RON min and you are expecting the 'brain' to retard it by 5RON - not gonna happen.
You should use SUL at the very least, but I have been advised to only use SUL with a booster or Optimax. I use Optimax as it is cheaper than SUL without the booster.
This is only info I am passing on - I'm no expert, but there are plenty of people on here who know what they are talking about!

 

BANG!

It is basically as Huw says! Be safe!!!! not sorry, get ya cash out for the super and booster

 

Jesus, when you say it's an import, where was it imported from?

If it's a Japanese market car I hope you haven't been driving it like that for very long, otherwise, as Brun says, Bang!

Optimax/other Super Unleaded plus octane booster is the only safe solution. Regular unleaded alone is a complete no-no, and Optimax alone isn't enough to be safe unless you're using a KnockLink and it's telling you the engine is in the clear.

[Edited by greasemonkey - 1/5/2004 8:33:50 PM]

 

what is octane booster? and what is better optimax or super unl?

 

Optimax is safer than SUL.

Octane Booster is an aditive you add to the fuel tank when you fill up, it raises the octane rating of your fuel to bring it closer to the spec the Japanese market cars are designed for.

 

optimax

consider getting the ecu remapped too (especially if you free up some power with a decat & filter)... if the car is MY96 or earlier, this will cost less than £100 if u go down the scoobyecu route.

 

Continual use of octane booster can cause damage to your CAT and there are also some reports of deposits left on lambda sensors causing other problems.

Another solution (though pricey but generally less than a remap) is to go for water injection which whilst not actually raising the RON value of your fuel will cool intake charge/cylinder temps down sufficiently to prevent detonation.

Using this method I've been running my '97 STI JDM on BP SUL / Optimax with no boosters for approx 15 months (30'000 ish miles) with no problems at all. Saying that I still take extra precations for trackdays and use booster also.