regular or middle grade gas?

Question

does it really matter if you put regular or middle grade gas in your car. Will middle grade gas last longer and give more gas mileage than regular gas?

Answer 1

It depends on your vehicle. Some vehicles can take advantage of the higher octane fuels, others can not.

You didn't specify the year, make and model of your vehicle so it is very difficult to give you a good answer. The easiest way to check if your engine can take advantage of the mid and premium grades of gasoline is to check to see if your engine has a knock sensor in it. Or if you know the compression ratio of your engine.

What occurs inside the engine is the piston compresses the space inside the cylinder. Typically when it hits the top (or close to the top) the spark plugs fires and forces the piston down. (aka power stroke).

Typically the higher the compression, the more power you can get. So you want to compress the piston as far up the cylinder as possible.

Lower grade fuels will begin to ignite at lower compressions. Typically due to the residual heat, while higher octane fuels resist what's known as spontaneous/pre ignition. So mid and premium fuels allow for engines to compress the air fuel mixture more.

If your car doesn't have a high compression engine, then you can't take advantage of this, and you'll just be wasting your money.

If your vehicle can take advantage of this, it will allow the greater compression of the air/fuel mixture and typically give your more power as a result.

To allow high compression engines to burn lower grade gasolines, manufacturers have placed knock sensors in engines to retard or delay spark so that your compression of air/fuel is not optimal. It allow the car to run, but you lose power and really wasted your money in purchasing the car because you aren't taking advantage of the engine's full potential.

Oh, and why is pre-ignition/spontaneous ignition bad. Well pre-igntion can occur anywhere inside the chamber and typically counter the direction of force that your spark generates. Typically it also results in "shock" waves as the multitude of flame fronts collide. This generates engine knock, and the shock waves can damage your piston and cylinder surfaces.

So...
Regular or middle grade. Depends on your car. If you car can take advantage of the middle grade, definitely because you get better performance. If your car can't take advantage of it then no, your just wasting your money.

Answer 2

My new '07 Chrysler 300 Touring with the 3.5 V-6 needs the middle grade. The owners manual states that it can be run on regular, but over time it could cause "drivability issues", whatever that means. I thought I would try regular. I had no problems with the first tank, but about halfway through the second tank, the "malfunction" light came on in the dash. Again, I read the manual... It said it could be caused by a loose fuel cap, or fuel quality. I had checked the cap when the light first came on and it was tight, so I called the service department of my local dealer and asked them about it. They told me that it was probably the quality of fuel I had in it, so I drove down to the station and filled it back up with premium, which gave me a tank full of mid range gas. After three cycles of starting, driving and shutting the car back off, the light went out and has stayed out ever since, so I'm am going to keep putting the middle grade in the car. Hope this helps....

Answer 3

First step look in your owners manual. It has nothing to do with mileage, it's all about how well your car will perform. Sports cars require higher octane fuel, regular old econo boxes do not. But sometime even though the manufacturer may require premium or mid grade you can use regular, my car is like that. That's why I said look in your owners manual.

Answer 4

it matters to the performance of the car. if you keep on using 87 which is regular you might end up hearing some knocking sound from your engine. but regards to the mileage difrrence there will not be huge diffrence perhapes few miles with a full tank of premium. if you have a new car then its just a factory recommendation that consumers to use the premium gasoline. but you dont have to cuz it aint going to break your engine down or anything!

Answer 5

you use any thing other then regular them your wasting your money most of the cars now adays are set up to run on regular

Answer 6

THE MFG. HAS A NOTICE AS TO WHAT OCT. TO USE IN THE CAR IF IT DOSEN'T SAY HIGH OCT. THAN USE REG GAS

Answer 7

yes it does matter..go for premium/supreme 91 octane..

Answer 8

No. Unless your car has to burn high test.