type of fuel..Reg. Vs Premium?

Question

I noticed car makers will say that a specific car needs regular fuel or premium fuel. Does it really matter? Is it going to hurt the car if I use reg. when it states premium? Premium is just soooo expensive!

Answer 1

If the manufacture states

Premium Fuel "Required". You must use premium fuel to prevent damage to the engine. It means you have a high compression engine and the premium fuel prevents what is classically known as knocking.

If the manufacturer states:
Premium Fuel "Recommended". You do not need to use premium fuel. Your engine has a knock sensor to prevent knocking. You may see a slight power loss/mileage loss using the cheaper fuel, but it won't hurt your engine.

Now the explaination:

Higher octane fuels have a higher resistance to something called pre-ignition. Basically making it harder for the fuel to combust until it is ignited by the spark plug. Actually that is what is meant by the octane ratings, it's a measure of how resistant a fuel is to ignition.

Using fuel of a higher octane, typically will not hurt your vehicles engine, while using a fuel of a lower octane will cause what is known as "Engine Knock". An engine that has high compression, will actually have places inside the cylinder that is hot enough to begin the ignition process that is at a point other than the spark plug. These points of pre-ignition are typically where the piston and cylinder walls meet. This will cause a flame front to start at a point other than the spark plug. If the flame front when the spark plug starts will eventually collide with the flame front generated by the pre-ignition. When these flame fronts collide, you'll get the shock waves. (and you'll hear these shock waves in the forms of "Knocking") These shock waves over time will do internal damage to your engine.

If your owners manual says "Premium Fuel Required", it means no knock sensor has been added, and you must use the higher octane fuels to prevent engine knock. If you're owners manual says "Premium/Plus Fuel Recommended", it typically means you've got that knock sensor that will basically tell the electronics to retard spark and minimize/prevent knock by igniting the fuel at a point that is less than optimal, but preventing engine knock/damage.

While Premimum fuel may be more expensive than regular fuel, the difference in cost actually doesn't appear to have changed much. (ie Plus is typically 10cents more per gallon and Premium is typically 20cents more per gallon) On a 15 gallon tank, it means $1.50 more for the plus, and $3.00 more for the premium. (Not a significant cost savings to make me want to take the chance I'll need my engine rebuilt for $2000+)

Answer 2

Use what the Manufacturer recommends otherwise you could damage the engine.
I know the feeling, I have a Nissan Maxima that needs premium fuel and it's about 30 - 40 cents more per gallon.

Answer 3

Manufacturers are generally fair with their assertions about the type of gasoline to power the engine. If it says premium, it needs premium.

Answer 4

I do know if your car is under warranty and some thing happens to the engine they do check the fuel grade and engine oil grade to make sure it is what was recommended. if not they will try to get out of fixing your car.

Answer 5

if you car calls for premium you better use it or be prepared to pay super big bucks down the road for engine repairs, if you don't want to use premium you better sell the car and get something else.