Premium gas?

[Rina120]

So I used to have a 94 525i and i used 89 octane gas.
Eventually, the gas tank imploded, I'm not sure if this is related to the gas or not.

Anyhow, I got rid of that car and now I have a 93 525i. The previous owners put premium gas only in it. Since I have had it (July), I have used 89, like I usedin my previous one.
This past weekend, I actually took a peek at that note in my gas tank and it says PREMIUM GAS ONLY.

So what gives? How come 89 was good for my 94 but I need premium for my 93? I thought you only had to use premium if you chipped the car?
What do you guys say?

[infinity5]

You should be fine so long as it's not knocking. Read your manual. theres a whole section on gas requirements (or there is in mine) and for my m60 it said something along the lines of "USE PREMIUM GAS ONLY!!!!! (and then a few lines down) but anyhting with at least 89aki is perfectly fine"
*shurg*





So I used to have a 94 525i and i used 89 octane gas.
Eventually, the gas tank imploded, I'm not sure if this is related to the gas or not.

Anyhow, I got rid of that car and now I have a 93 525i. The previous owners put premium gas only in it. Since I have had it (July), I have used 89, like I usedin my previous one.
This past weekend, I actually took a peek at that note in my gas tank and it says PREMIUM GAS ONLY.

So what gives? How come 89 was good for my 94 but I need premium for my 93? I thought you only had to use premium if you chipped the car?
What do you guys say?

[Springfield1952]

The gas tank imploded?? What's up with that?

Curt.

[chamilun]

is 89 aki the posted number on the pump? ive been running 93, but if 89 would be good, id switch. the octane rating and sulfur content are not related (m60 engine).'

i thought that 'aki' or anti-knock index was different than the number shown on the gas display.

any opinions on this??

[Bill R.]

vanos has knock sensors and the gas they specify is 89 aki and the older m50 specifies 90 aki since it has no knock sensors If yours is a real early 93 it could have been a m50 motor not the m50tu, if its a later motor then it should be the same as your 94 was...






So I used to have a 94 525i and i used 89 octane gas.
Eventually, the gas tank imploded, I'm not sure if this is related to the gas or not.

Anyhow, I got rid of that car and now I have a 93 525i. The previous owners put premium gas only in it. Since I have had it (July), I have used 89, like I usedin my previous one.
This past weekend, I actually took a peek at that note in my gas tank and it says PREMIUM GAS ONLY.

So what gives? How come 89 was good for my 94 but I need premium for my 93? I thought you only had to use premium if you chipped the car?
What do you guys say?

[tdgard]

This summer I read an interesting newspaper article about this subject. They had spoken with several auto manufacturers about octane. The quote I remember most was from a Porsche engineer that basically said sure we put premium stickers all over our cars, but they also have to work all aver the world including those places where premium is not available. All the manufacturers stated that you would not be doing any harm—just maybe a slight decrease in performance. Maybe Mark can chime in and explain why, after chipping, we need to put in premium. Is it a drivability thing, or would you just not be getting the full effect of the chip?

[George Davis]

Chamilun, in the US the number on the gas pump is the aki.

[Derek A.]

One of the benefits of premium fuel is the extra detergents in them. Have seen an intake tract or two that are really messed up due to crap gas.

[Rina120]

Hmmm.interesting. So how can I tell if I have a tu or not?
And I have never heard a knocking noise. Is it obvious? Will I know it when i hear it?




vanos has knock sensors and the gas they specify is 89 aki and the older m50 specifies 90 aki since it has no knock sensors If yours is a real early 93 it could have been a m50 motor not the m50tu, if its a later motor then it should be the same as your 94 was...

[Bill R.]

m50tu if its 9/92 then it could go either way and you have to look at the motor to determine if its vanos or not... vanos will have a bulge on the drivers side of the timing cover up near the top of the head





Hmmm.interesting. So how can I tell if I have a tu or not?
And I have never heard a knocking noise. Is it obvious? Will I know it when i hear it?

[Torque]

few dollars a week should not prevent you from getting premium for your bmw.

i put 93 in my m20 even though i believe the manual says that 89 is good for it. ;)

[Dave M]

I routinely fill my M50 (91) with 87-89 octane with no ill-effects. For peace of mind I occasionally fill with 91-93 octane. I 'religiously' monitor gas mileage and have noticed no significant change between grades.

[Torque]

I routinely fill my M50 (91) with 87-89 octane with no ill-effects. For peace of mind I occasionally fill with 91-93 octane. I 'religiously' monitor gas mileage and have noticed no significant change between grades.
inside of gas tank door says 'Premium Gasoline Only' on my dads 91 m50...

[Mobius]

few dollars a week should not prevent you from getting premium for your bmw.

i put 93 in my m20 even though i believe the manual says that 89 is good for it. ;)If your manual recommends 89, and you're putting in 93, all you're doing is wasting your money, decreasing performance, and (probably) increasing your fuel consumption.

You're doing a good job of buying into the (obviously effective) "premium is better for your car" marketing model used by the oil companies for so long now. -It's just not true, though.

Simply, octane ratings show a fuel's resistance to combustion. Higher-octane fuels are harder to burn - which is why engines which run high compression ratios or more advanced spark timing need them to prevent pre-ignition.

I'll stop - I'm just rehashing what's said here (CHEVRON says this, by the way): http://www.chevron.com/prodserv/fuels/gas_qanda/api_octane.shtml

Just a little quote:

Q. What is octane?

A. Octane is a measure of a gasoline's ability to resist knock or pinging noise from an engine. In older vehicles, knock may be accompanied by engine run-on, or dieseling. Knock is the sharp, metallic-sounding engine noise that results from uncontrolled combustion. Severe knocking over an extended time may damage pistons and other engine parts. If you can hear knocking, you should have your engine checked to make sure it is calibrated correctly and does not have a mechanical or electrical problem, or use a higher octane gasoline.

In most vehicles no benefit is gained from using gasoline that has a higher octane number than is needed to prevent knock. However, in some vehicles equipped with a knock sensor (an electronic device installed in many modern engines that allows the engine management system to detect and reduce knock), a higher octane gasoline may improve performance slightly.

Also; here:
http://www.shellus.com/products/product_info/gasoline_faq.html

There's absolutely no benefit from premium gas unless your engine NEEDS it.

[infinity5]

I definatly agree, but i'm pretty sure some of the engines were designed and built to use 93. and then someone pointed out there are places you can't get 93, and adaptive computer maps were added and knock sensors were added and various other engine components were adjusted. thats why chips require 93.. they get rid of the flexability becuase it sacrifices effciency... and in that case higher octance would be 'better' for your car. Anyone know for certain? I'd think that were true.. but i'm sure it depends heavily on your engine. i think it pivots on whether or not the engine, unchipped, adjusts its self relative to gasoline grade. if it did, then it would matter.. if not, then it doesn't.

Also i wonder about ther detergents.. I've heard both sides... it sounds like they are cleaner, but the gains are fractional.



If your manual recommends 89, and you're putting in 93, all you're doing is wasting your money, decreasing performance, and (probably) increasing your fuel consumption.

You're doing a good job of buying into the (obviously effective) "premium is better for your car" marketing model used by the oil companies for so long now. -It's just not true, though.

Simply, octane ratings show a fuel's resistance to combustion. Higher-octane fuels are harder to burn - which is why engines which run high compression ratios or more advanced spark timing need them to prevent pre-ignition.

I'll stop - I'm just rehashing what's said here (CHEVRON says this, by the way): http://www.chevron.com/prodserv/fuels/gas_qanda/api_octane.shtml

Just a little quote:


Also; here:
http://www.shellus.com/products/product_info/gasoline_faq.html

There's absolutely no benefit from premium gas unless your engine NEEDS it.

[Mobius]

thats why chips require 93.. they get rid of the flexability becuase it sacrifices effciency... and in that case higher octance would be 'better' for your car. Anyone know for certain? I'd think that were true.. but i'm sure it depends heavily on your engine. i think it pivots on whether or not the engine, unchipped, adjusts its self relative to gasoline grade. if it did, then it would matter.. if not, then it doesn't. Oh yeah, of course. If your chip calls for a certain octane, you'd better be using it. However, if your manual says '89' and your engine is totally stock, there's nothing to be gained from going higher than 89 octane.

Of course, most any engine made in the past 15 years will likely have a knock sensor, and will use it to retard timing and such when knock occurs - and of course running higher-octane fuel will reduce the chance of that occuring. But if the manual calls for 89, and you have to put 93 in to keep it from knocking, you have bigger problems.
Similarly, if the manual calls for 89 and you have no knock problems when you run 89, you probably aren't going to gain much by running 93. In fact, due to the nature of higher-octane gas, if your engine isn't built to take advantage of it, you will probably just reduce its efficiency.


Also i wonder about ther detergents.. I've heard both sides... it sounds like they are cleaner, but the gains are fractional.Really; the amount of any sort of additive probably varies more between gas stations than it does between grades of gas. If you're concerned about that, add some Techron yourself.