oh dear.....fuel question...help!!

[iamjj]

just went via texaco on my way home to top up for tomorrow.

wasnt paying too much attention and put super unleaded in 318i about Ԛ£20 worth. there was aboutԚ£5-Ԛ£10 of normal already in there.

i know nothing about this stuff, is this a problem or will it run fine?

thanks guys

[E30Mark]

It will run the same, don't worry.

[Brianmoooore]

Leaded, four star, unleaded, super unleaded, even a little bit of diesel, will not harm your engine in the slightest.

[astondg]

I will just expand on that slightly to give you a bit more information in case you are interested, if not just stop reading now.

Unleaded and uuper unleaded are the same petrol it's just that super unleaded has a higher octane rating than normal unleaded so it is better for higher performance engines but your engine will use it perfectly fine too. I'm not sure but your car might actually gain very slightly from using super unleaded, but is perfectly happy on normal unleaded too. Putting in both will give you an octane rating somewhere in between.

Aston

[alan325i]

Agree with the diesel, i put Ԛ£12.00 of the stuff in mine once, bag of shit low speed, but over 3000k revs, boy did it fly, just a pity about the smoke screen i was leaving behind me

As for super unleaded will be fine, just more expensive

[Brianmoooore]

Unless your engine is fitted with detonation detectors (knock sensors), such as those on the M50, then you will gain absolutely nothing from using petrol with a higher octane rating than the minimum needed to prevent pinking.
I normally run one of my 325s on 115 octane fuel, but it gains nothing powerwise.

[astondg]

That is why I said might gain, I didn't know what the 318i engine has but now I'm guessing it doesn't have knock sensors. Even if there is a gain on most normal engines I think it will be very slight because they don't have (or have only basic) fuel and ignition maps for higher octane petrol.

My 323i has been tuned to run on 98 octane and from what I am told that made a difference to power even though it has no knock sensors and it can still run on 96 octane unleaded, but it doesn't run as well (I don't think it has any detonation problems though).

Aston

[iamjj]

thanks guys...was worrying me there for a second

[Brianmoooore]

That is why I said might gain, I didn't know what the 318i engine has but now I'm guessing it doesn't have knock sensors. Even if there is a gain on most normal engines I think it will be very slight because they don't have (or have only basic) fuel and ignition maps for higher octane petrol.

My 323i has been tuned to run on 98 octane and from what I am told that made a difference to power even though it has no knock sensors and it can still run on 96 octane unleaded, but it doesn't run as well (I don't think it has any detonation problems though).

Aston

If your car has no knock sensors, and you can tell a difference between 96 and 98 octane fuel, then you have detonation on the lower octane fuel.

[astondg]

Could be. I am just going on what the mechanic told me. I can't tell any difference (I haven't ever used lower octane fuel in it) but apparently the dyno can. The mechanic that fitted and tuned the computer said there was no detonation but it ran worse and made slightly less power. However I have just found out that when he fitted it he failed to notice the base timing was out 10 degrees so I am also willing to believe he failed to notice any knock or he made up the whole thing.

Sorry to hijack the thread. Your car will be fine, good luck with it.

Aston