[VWtoBMW]

Originally Posted by bobblehead

for alll those who do not care much for the leased vehicle, if gas cost is your concern, then why not just lease the cheapest Honda or Toyota or Kia.

Exactly

[jedpause]

I appreciate you're talking about the US, but in EU (UK more specifically) premium fuel usually means Shell V-Power Or BP Ultimate which is the performance stuff 97/98 Octane).

You can get 87, but most go for Normal = 90 due to the price. Performance is much more expensive, 8p a litre (about $10/tank).

The point I am making is whilst I agree to an extent that if you are buying a luxury car, this would be insignificant, however as a company car when you pay fuel and tax on the benefit (UK Tax stings you!), then that's why I don't put performance fuel in.

Moreover, I give the car back every 4 years so don't care... and recent studies (Top Gear, What Car, AA etc. show no tangible difference in performance).

Each to their own

[COBodom]

Methinks we are missing a point here.

The question here is what is considered “premium”. BMW recommends 89 and 91. Turbo engine will sooner or later choke on 87. Lease or purchase; 89 is perfectly fine.

Now, off to catch that expiring holiday special at the local Yugo dealer. Can’t wait to finally be able to afford 91.

[The X Men]

Originally Posted by COBodom

The question here is what is considered “premium”. BMW recommends 89 and 91. Turbo engine will sooner or later choke on 87. Lease or purchase; 89 is perfectly fine.

I am going to open up a can of worms here, the new Hyundai 2.0 turbo engine recommands 87 octane.

[Amleto63]

I use Shell V-Power or Agip Blue Diesel only. No black smoke and issues at all.

[COBodom]

Originally Posted by The X Men

I am going to open up a can of worms here, the new Hyundai 2.0 turbo engine recommands 87 octane.

Oh no..…..wish I read your post earlier. Should have gone to Hyundai instead of Yugo.


On a serious note though, I don’t know anything about Hyundai, but I am sure you’re right. However, any AUDI/VW/BMW turbo that I had always got the “check engine” light after a tank or two of 87.

[M_528i]

only use Shell V power and nothing else.

[The X Men]

Originally Posted by COBodom

Oh no..…..wish I read your post earlier. Should have gone to Hyundai instead of Yugo.


On a serious note though, I don’t know anything about Hyundai, but I am sure you’re right. However, any AUDI/VW/BMW turbo that I had always got the “check engine” light after a tank or two of 87.

The Hyundai 2.0 turbo engine can also produce 275 HP, a bit more than BMW's 240 hp.

[vdubturbo]

I see these threads pop up from time to time on various forums and they annoy the crap out of me for a couple reasons. Believe it or not, there IS science and engineering behind the recommended octane rating. Because most people don't understand what octane really is, the discussions always revolve around the periphery of the topic. So I'll explain and you can chose to listen or not... I taught internal combustion theory and application at a university, so I feel somewhat qualified to open my mouth (though people rarely care)...

Octane is generally defined as a fuel's resistance to preignition and detonation. To the layman, this is it's resistance to pings and knocks. The higher the octane rating, the more resistant a fuel is to being ignited by the temperature and pressure within the cylinder (and not the spark plug). There is a tradeoff however... the higher the octane rating, the slower the fuel will burn (I'll get to that in a little).

Engines are designed with a certain compression ratio. The higher the compression, the more the fuel must resist igniting on it's own... thus a higher octane requirement. Turbocharges effectively increase the cylinder pressure by forcing additional air charge into the cylinders (duh). So while a turbo car might advertise a static compression ratio of 9.5:1, with the turbo is working that number may actually be considerably higher. This is why turbo cars generally run higher octane fuels.

Modern vehicles have sophisticated sensors to monitor the performance and safety envelope of the engine. Because there's a variety of factors that can induce preignition (other than low octane) like load, temp, ignition and valuve timing, or altitude, the engine's computer will adjust certain variables to keep the engine in a "safe zone"... e.g. no condition where preignition or detonation is present.

So here's why I think using lower than specified octane fuel is a bad idea: By using 87 or 89 instead of 91 or 93, you essentially force the engine into a state where it has to constantly correct for preignition or detonation. For the engine to do this, it must first DETECT the ill-advised condition. This means that some preignition must occur before the ECM can account for it. And because computers are logic based, it doesn't know what is causing the condition, so it will constantly check & adjust, check & adjust...

It was previously stated that no reliability problems are generally identified with short term exposure to this situation (which may be true), but I have to believe that over the long term, those conditions will take it's toll on the internal engine components. If anyone has ever seen what detonation can do, you'll appreciate how catastrophic it can be.

So in my opinion, NO, do not run lower octane fuel unless you're prepared to pay the consequences down the road. It's not a matter of "zippiness" or MPG's, it's a matter of wear. Yes, low octane gas will degrade the performance of your car... but that's a SAFETY mechanism, not a convenience because you are too cheap to purchase the correct fuel or wanted a more expensive car than you really could afford.

One other point... if you have a car that requires 87 and you run 91 because you want to "treat" your car, or get some more power... you're a fool. Running higher than the required octane will possibly degrade performance because it burns slower (as stated in my first paragraph).

Hope this helps. Flame suit on.

[Boulder Bill]

Fascinating. Really. You sound as close to a rocket scientist as we are likely to see on this forum.

I have always run premium and will continue to do so. My sense was essentially what you have stated - I wanted to protect the engine from unecessary wear and the marginal cost was insignificant.

Going back to the OP, if you have the car for 3 years and then turn it in, perhaps you just don't care. I wouldn't know, since I buy, hold and drive. I suppose those on a lease have their decision to make. But thanks for the thoughtful post.

[vdubturbo]

Haha thanks I wish though!

You're right though about the lease. It's up to the lease holder, but that's kind of a crappy thing to do to the next owner...

[qadhi79]

next thing you know..someone will come here asking if people properly clean their leased car or not or if they just clean it from outside..lol

don't be cheap..leased or rented..treat it good!

[bubbahead]

I bought the 4.4 twin turbo 550ix for a reason......I wanted the power. Even though its a lease, I want the car to perform on a optimal level. I put premium

[jedpause]

Further to my first response, and after reading vdubturbo's writeup... I studied a bit more.

Turns out regular and premium in UK have higher octane ratings than US. Seems regular here in UK is aligned with BMW minimum requirements, so our Premium (99 Octane) is much higher than needed, i.e. our regular is just fine and Dandy to keep the engine healthy....

i.e. US regular is below spec I believe, premium aligns it with BMW recommendations

That's why I don't have any inclination to buy premium in UK despite it being crazy expensive anyway.

[vdubturbo]

Interesting jedpause!

[NW5er]

I put premium in loaners too. Just feels right since it is what the factory recommends.

[TimeFor]

Are you serious? There is a huge performance drop between 91 and 87. Its very noticeable to me and certainly worth the extra $3 per tank. I don't treat my car any differently because I lease it.

I leased this last time because I found myself buying a new car every 2-3 years anyways. I don't feel there is any real difference between lease and own. The only minor difference I see is that I don't have the hassle of getting rid of the car when I'm ready for a new one.

-Time

[cafelatte04]

i have no money! but i using premium gasoline

[Alan l.]

I choose my car expecting it to give me all 300HP that Bmw said it has. I'm not going save a few bucks by putting in cheap gas so i could have less.

Its like someone buying a top of the line Macbook Pro and then go cheap by hooking it up with dial up connection because you saved a few bucks by not getting cable/Fios. Lease or finance I treat my cars as if its nearly a member of the family (my wife hates me for it lol)

Alan

[M_528i]

Originally Posted by Alan l.

I choose my car expecting it to give me all 300HP that Bmw said it has. I'm not going save a few bucks by putting in cheap gas so i could have less.

Its like someone buying a top of the line Macbook Pro and then go cheap by hooking it up with dial up connection because you saved a few bucks by not getting cable/Fios. Lease or finance I treat my cars as if its nearly a member of the family (my wife hates me for it lol)

Alan

+1 If what to save fuel then should be driving a Toyota and not BMW

[sanf]

It's totally up to you. The car is still gonna run. But if you care on how the car performs, how others look at you or for whatever reason, then premium it is.

[Amleto63]

Originally Posted by M_528i

+1 If what to save fuel then should be driving a Toyota and not BMW

Not agree. Try driving a BMW 2 liters diesel and let me know