I know that I should keep burning the higher octane gas, but as everyone knows, it is getting very expensive. Will I do any damage if I use the lower octane (87) and only put the premium in every few tanks? My salesman friend says that is what he does with his, but I just wondered what everyones opinion was.

Not sure on the X3 but straight from the manual from my 2000 3 Series it says
"Use unleaded gasoline only.
Recommended fuel: Premium with a
minimum octane rating of 91 AKI.
BMW engines are equipped with knock
sensors and will adapt automatically to
different octane ratings, provided that
the minimum octane requirement
(87 AKI) is met.
Fuels with higher octane ratings will provide
enhanced performance and lower
fuel consumption, while the use of fuels
with lower octane ratings will have the
opposite effect."

So probably the same on your X3 as well as all other modern BMWs

I have used it. Like the manual says, there seems to be a slight performance loss, but I am not sure if that is just the power of suggestion or the real facts of life.

That said, I am almost positive that I get better gas mileage from the good stuff.

Cheers,
D

Expensive??! Premium fuel is the cheapest its ever been! (relatively speaking) Think of it this way... when gas was $1.00 a gallon, premium was 20 cents more per gallon (20% increase in price). Now that gas is $4.00 a gallon, premium is STILL only 20 cents more per gallon (5% increase in price).

When gas was $1 a gallon, premium set you back about $3.50 more per tank. At $4 per gallon, it STILL only sets you back about $3.50 more per tank!

18 gallons x $1 per gallon = $18 ; 18 gallons x $1.20 per gallon = $21.60 (+$3.60)
18 gallons x $4 per gallon = $72 ; 18 gallons x $4.20 per gallon = $75.60 (+$3.60)

If you can't afford the gas, you shouldn't have bought the car. And please search, we've been covering this since gas was $2.00 a gallon.

Expensive??! Premium fuel is the cheapest its ever been! (relatively speaking) Think of it this way... when gas was $1.00 a gallon, premium was 20 cents more per gallon (20% increase in price). Now that gas is $4.00 a gallon, premium is STILL only 20 cents more per gallon (5% increase in price).

When gas was $1 a gallon, premium set you back about $3.50 more per tank. At $4 per gallon, it STILL only sets you back about $3.50 more per tank!

18 gallons x $1 per gallon = $18 ; 18 gallons x $1.20 per gallon = $21.60 (+$3.60)
18 gallons x $4 per gallon = $72 ; 18 gallons x $4.20 per gallon = $75.60 (+$3.60)


:confused
what?
did this make sence to anyone?

Expensive??! Premium fuel is the cheapest its ever been! (relatively speaking) Think of it this way... when gas was $1.00 a gallon, premium was 20 cents more per gallon (20% increase in price). Now that gas is $4.00 a gallon, premium is STILL only 20 cents more per gallon (5% increase in price).

When gas was $1 a gallon, premium set you back about $3.50 more per tank. At $4 per gallon, it STILL only sets you back about $3.50 more per tank!


Gas before the big price increses...
18 gallons x [when regular gas was]$1 per gallon = $18
18 gallons x [when premium gas was]$1.20 per gallon = $21.60 (a difference of $3.60)

Gas after the big price increases....
18 gallons x [now that regular gas is] $4 per gallon = $72
18 gallons x [now that premium gas is] $4.20 per gallon = $75.60 (STILL only a difference of $3.60)

:confused
what?
did this make sence to anyone?


Re-read my edited version... see if it makes more sense...

My point was that if you were willing to spend $3.50 more per tank when you could fill your tank for $20, you should still be willing to spend that same $3.50 now that a tank of gas costs $75. (The price difference between regular and premium is still only 20 cents per gallon even though a gallon is 4 bucks instead of 1).

Exactly, it's an algebra equation
x*y=$ for regular or
x*y+.20 for premium

where x = how many gallons and y = the price of gas, it's a constant equation of the difference between the cost of regular and the cost of premium that doesn't change now if it was something like

x*y=$ for regular or
x*z=$ for premium, where Y and Z weren't anything of any relation to each other than we'd be paying different prices, and it might be crazy expensive, not just a drop in the bucket in comparison.

At it's current price, getting premium throughout a tankful is cheaper than 1 gallon of gas, and if you get say 28mpg with premium and 25mpg with regular (hypothetical, but very probable numbers here) you'd be getting 54mpg more with premium (about 2 gallons difference, also using a 18 gallon tank in this equation) therefore saving you almost 2 gallons of gas, which at the current price 1 gallon is more than getting premium, so you'd be saving about 60% on those 2 gallons or saving 11% total for the whole tank by just getting premium vs skimping and doing regular.

Bottom line you should just get remember in the long run, it's cheaper to use premium than to use regular in our cars, even if it's just for MPG, forget anything about degraded engine performance/wear from possible knock conditions and not having the cleaning additives that are now in 91+ octane fuel (and some others) that helps our engines stay a little cleaner between things like seafoaming

ok,

now the Re-edited is understandable.

One issue here is with cheaper gas you get poorer gas mileage... wiping out any cost savings.

exactly see post above

premium for sure:)

I get better milage using premium and I agree it is relatively cheaper now.

I always put 98 octane in all of my cars, goes harder, smoother and sounds better

I always put 98 octane in all of my cars, goes harder, smoother and sounds better

If you have problems with your valves I wouldn't tell your tech you've been putting 98 in your cars.

Unless you raise your compression ratio, there really is no use in putting a higher octane fuel in your car and in fact it's actually bad for it.

your car could run like crap, and it will guzzle if you put the cheap stuff in. do what the manual says and you should be just fine, if your worried about gas consumption, try driving like a granny. good luck.

More mpg. If your car ask for premium.

there is absolutely no harm in using premium, ever
and yes it is relatively cheaper than it used to be
and yes one or two mpg increased fuel economy will pay for
the increased price
plus your car will run better and won't blow up
Geez people its like 5%! Put retread tires on and splurge on the premium!
Sorry, I just can't believe we debate this!

there is absolutely no harm in using premium, ever
and yes it is relatively cheaper than it used to be
and yes one or two mpg increased fuel economy will pay for
the increased price
plus your car will run better and won't blow up
Geez people its like 5%! Put retread tires on and splurge on the premium!
Sorry, I just can't believe we debate this!

i'd laugh if a engine went kaboom after putting in regular :devillook