93 Octane OK for Stock B5?
#2
07-20-2009, 10:14 PM
Less detonation in the motor, causing longer life of the pistons/rings. Just don't put below 91 octane in the tank, ESPECIALLY if you plan to add more boost pressure.
#3
07-20-2009, 10:17 PM
It depends. If the manual says that premium is REQUIRED, then you should be using 91-93 depending on elevation. If it says RECOMMENDED then you can get away with regular.
Some people think that octane rating is a measurement of the performance, power, quality, etc of the fuel. This is not true. The octane rating measures the fuel's resistance to preignition, also known as knocking.
The octane level required for your car depends on compression ratio, age of the engine, and how well it's been maintained. Some older cars will need to use mid-grade or premium fuel if they are in poor condition, even though they only require regular.
Even if the manual says that premium fuel is required, you could get away with regular with only minor performance losses due to today's advanced computer-controlled engines. If your car says that it requires regular fuel then you will absolutely be wasting your money paying for anything more (unless your engine is in poor condition and is knocking).
If you've been running it on regular, personally I would stay with regular to save money. Some people might say premium. If it had an aftermarket turbo I would say that you need to be using premium, but it's stock, so I don't think there would be much to worry about.
Just take a look at the manual; if it says premium is recommended but not required, then I would go with regular.
Some people think that octane rating is a measurement of the performance, power, quality, etc of the fuel. This is not true. The octane rating measures the fuel's resistance to preignition, also known as knocking.
The octane level required for your car depends on compression ratio, age of the engine, and how well it's been maintained. Some older cars will need to use mid-grade or premium fuel if they are in poor condition, even though they only require regular.
Even if the manual says that premium fuel is required, you could get away with regular with only minor performance losses due to today's advanced computer-controlled engines. If your car says that it requires regular fuel then you will absolutely be wasting your money paying for anything more (unless your engine is in poor condition and is knocking).
If you've been running it on regular, personally I would stay with regular to save money. Some people might say premium. If it had an aftermarket turbo I would say that you need to be using premium, but it's stock, so I don't think there would be much to worry about.
Just take a look at the manual; if it says premium is recommended but not required, then I would go with regular.
#4
07-20-2009, 10:28 PM
#5
07-20-2009, 10:48 PM
As a general rule any car with a turbo should be fed a heathly diet of premium due to the different compression.
#6
07-20-2009, 11:02 PM
^^^^Well according to your link all audi's should use 87, thats just plain stupid.
My B5 started to knock at around 15 psi, (according to knock sensor not sound) which isn't that much more than stock, so i would be hard pressed to just go slapping 87 in there. The ECM will compensate for knock to a certain point, but external heat (the weather) also plays a factor in pre-ignition, so if you live in phoenix you might as well put a bullet through the block of the engine running 87 octane. The example the guy gives in the 99.epinions.com blog was a Ford F150, well no truck on earth needs more than 87 octane unless its Dodge's SRT-10 with a Viper motor in it. They don't produce enough compression to knock, they get their power from displacement and the stroke of the engine. I can write a book about every car available today and i would agree that only about 30 of them actually need premium as they sit from the factory, but all of them are either high compression performance engines, or force fed. The factory B5 A4 with 7-9 psi is a higher compression turbo engine, which just BARELY accepts 87 octane, add a couple PSI in a hot climate and you will be doing damage.
2.8L motors, can pretty much run whatever they like.
My B5 started to knock at around 15 psi, (according to knock sensor not sound) which isn't that much more than stock, so i would be hard pressed to just go slapping 87 in there. The ECM will compensate for knock to a certain point, but external heat (the weather) also plays a factor in pre-ignition, so if you live in phoenix you might as well put a bullet through the block of the engine running 87 octane. The example the guy gives in the 99.epinions.com blog was a Ford F150, well no truck on earth needs more than 87 octane unless its Dodge's SRT-10 with a Viper motor in it. They don't produce enough compression to knock, they get their power from displacement and the stroke of the engine. I can write a book about every car available today and i would agree that only about 30 of them actually need premium as they sit from the factory, but all of them are either high compression performance engines, or force fed. The factory B5 A4 with 7-9 psi is a higher compression turbo engine, which just BARELY accepts 87 octane, add a couple PSI in a hot climate and you will be doing damage.
2.8L motors, can pretty much run whatever they like.
#7
07-20-2009, 11:33 PM
Aw man! Only stopping at 87? I was talking about putting 85 in there! 
Just kidding. Yes, location is also a factor. I wasn't aware all B5 A4s were turbo, in that case it would be better to use higher than regular.
Just kidding. Yes, location is also a factor. I wasn't aware all B5 A4s were turbo, in that case it would be better to use higher than regular.
#9
07-20-2009, 11:48 PM
our ECU can/will pull timing if you put too low octane in there and it starts to preignite. so its not going to destroy your car, but you will loose power especially on a 1.8t. if you have a chipped car which is tuned for 93 octane you will loose a lot of power by using 85/87.
