Gas - supreme or not

H

hoangtu69

New member
With the high gas price, I heard you don't need to use supreme gas if your Z4 is old. I have a 2003 Z4 3L.

Can I use regular unleaded gas for it? Are there any downside for it?

Thanks
 
I wouldn't do that, high performance motor not made for lower octane fuel. Check your owners manual. :thumbsdown:

You should log in under the "Newbie Forum" and introduce yourself, pics would help.
 
Also, check out the definition of 'expensive' here... And that's regular unleaded. Add 5-7p per litre for premium :cry:
 
Check your owner's manual for the minimum and recommended octane levels, in some areas, a mid grade fuel will meet the requirements. It's been decades since a BMW engine was made to run on regular petrol. Age has nothing to do with it, it's a matter of compression ratio vs. the risk of detonation or knock. Low octane fuel will knock. This is much worse than it sounds, it can severely damage your engine. Though the engine has a knock sensor, detonation has to occur for it to sense it -- BAD! Then the ECU will severely retard the timing to stop the knocking, causing significant performance degradation. You will save nothing using low octane fuel and you risk engine damage. Don't do it!
 
bcworkz said:
Check your owner's manual for the minimum and recommended octane levels, in some areas, a mid grade fuel will meet the requirements. It's been decades since a BMW engine was made to run on regular petrol. Age has nothing to do with it, it's a matter of compression ratio vs. the risk of detonation or knock. Low octane fuel will knock. This is much worse than it sounds, it can severely damage your engine. Though the engine has a knock sensor, detonation has to occur for it to sense it -- BAD! Then the ECU will severely retard the timing to stop the knocking, causing significant performance degradation. You will save nothing using low octane fuel and you risk engine damage. Don't do it!
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+1. Check the manual, it'll say what the lowest acceptable fuel quality is. BMW engines sold in the US are mapped for lower quality fuel than in Europe - hence the lower bhp figures you guys have.
 
Bit of a tricky one for us Europeans to answer as the one thing I noticed when in the US recently is that even your premium fuel is 93 ron and of a lower octane rating than our standard fuel 95 ron.
Though you may not think it given how cheap fuel is in the US I'd stick to good stuff.

We are currently paying around $8.00 a US gallon and more if you want super / premium.
 
just had a quick look in the handbook page 75 and it says "the minimum permissible grade is regular-grade unleaded petrol, octane number 91 RON" Mine pinks on 95 which is what I first ran it on now only use super/plus 98.
 
US octane is presented in AKI units, which is an average of MON and RON methods. The result is the AKI is 4 to 5 points less than RON, so a US 91 AKI is about the same as 95 or 96 RON. My understanding of the different HP ratings is due more to general fuel quality issues than strictly octane ratings.
 
shadowdrgn0 said:
sorry for the thread jack, but why are prices so ungodly high in europe?
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Tax. With fuel there's so much tax that there's tax on tax.

Import tax, fuel tax, value added tax (in that order I believe). Nicely shown in this graph here: http://www.abd.org.uk/taxtable.htm
 
I may have to try running mine on 98 ron one more time just to re-confirm to myself that I've never been able to spot even the slightest difference, and even when overdue a service and in need of new sparks my car made good bhp on the rollers running 95 so it can't be that bad :)
 
I just tried filling up with super dooper petrol, got 16 litres in then the pump ran out!! Great now I have all the sludge n crap from the bottom of their tank!!!
 
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