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I have noticed that lots of foreign automakers say that there vehicles require premium fuel. I notice this from Mitsubishi, BMW, Mercedes, and some others. What happens if you don't put premium in these vehicles? Also, when you purchase these vehicles, are you told this or does the dealer not care?
I have noticed that lots of foreign automakers say that there vehicles require premium fuel. I notice this from Mitsubishi, BMW, Mercedes, and some others. What happens if you don't put premium in these vehicles? Also, when you purchase these vehicles, are you told this or does the dealer not care?
Im sure the window purchase sticker states what fuel it needs, as well as the fuel door and sometimes they even put the warning near the fuel light on the dash.
Some of the reason for the "premium" fuel requirement is the computer mapping for the motor, which may require the higher octane fuel for it's proper performance.
But, some of the manufacturer's are also finding that the lower grade fuels that don't have the same "additive" pack as the premium fuel are causing FI system problems, fouled intake manifolds and intake valves, plugged injectors, etc. The vapor pressure of the lower octane fuel may be out of the range that the car's sensors and FI system are designed to control, with starting and running problems resulting.
The long term problems from poorer gasoline can be cumulative and expensive to repair.
IMO, if you're going to spend the dough to buy an expensive performance car, using cheap fuel is a very false economy when the motor was specifically designed to run on premium.
The number of cylinders does not determine the fuel rating. The compression ratio and/or method of induction does. For instance, how do you suppose Honda gets 200HP out of a 2 liter engine? Answer: high compression. You know what happens when you put low-octane gas in a high-compression engine? You get pre-ignition (that is, until the computer dials down the spark timing until it stops pre-igniting). You know what happens to your engine when it pre-ignites one too many times? KA-BOOM! Now, computers have gone a long way toward preventing engine damage from pre-ignition; you could even theoretically run tank after tank of regular-grade gasoline through a modern car that optimally runs on premium grade. But you'll lose gas mileage that way and risk fouling up your injectors unless you constantly run additives.
Some of the reason for the "premium" fuel requirement is the computer mapping for the motor, which may require the higher octane fuel for it's proper performance.
But, some of the manufacturer's are also finding that the lower grade fuels that don't have the same "additive" pack as the premium fuel are causing FI system problems, fouled intake manifolds and intake valves, plugged injectors, etc. The vapor pressure of the lower octane fuel may be out of the range that the car's sensors and FI system are designed to control, with starting and running problems resulting.
The long term problems from poorer gasoline can be cumulative and expensive to repair.
IMO, if you're going to spend the dough to buy an expensive performance car, using cheap fuel is a very false economy when the motor was specifically designed to run on premium.
+1 and to add to this, using a lower octane fuel in a car that should be run on the higher octane can also lower your fuel economy. The ECU will retard timing and richen the mixture to compensate for the reduced octane, which not only reduces power but also efficiency, meaning your mileage goes down and you didn't actually save any money buy filling up with 87.
Well you'll still probably experience short-term savings, especially with premium now inching up to 25c/gal over regular. (This trend pisses me off, by the way. What ever happened to the days when premium was 10c/gal over regular and that was it?) But there are potential long-term consequences to running rich all the time, such as fouled plugs and injectors, more pollution and shorter catalytic converter lifespan. Which reminds me, that's another reason why you're seeing more and more high-octane engines: they make it easier to meet ever-tightening emissions standards.
I use the regular unleaded and only fill up with premium once a month. My car seems to run okay. I take it in for the regularly scheduled maintenance and have not had any bad reports yet. I've been doing it this way for a couple of years now. At first all I used was premium to fill up. I just figure gas is gas, but I'm a girl - what do I know!
Somebody at the dealership told me it wouldn't harm my engine if I used the regular as long as I filled up with the premium occassionally.
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