Premium, unless called for (usually for higher compression engine or advanced timing), is actually harder to ignite (that is why high compression engines require it to fight detonation or pre-ignition). It does no good at all unless it is preventing detonation. Otherwise you want to run 87/89 octance (89 if you are getting some pinging under acceleration) to get complete "explosions". I know some will say different but that is the reasoning behind higher octane levels. Put in 87 octane and consider the savings added mpg$.
2006 Jeep Liberty CRD...Founder of L.O.S.T.
OME 2.25" Lift w/ Toyo Open Country HTs 235/75/16s
ASFIR Alum Eng/Tranny/Transfercase/Fuel Skids
2002 Air Box Mod...Air Tabs (5) on Roof...(3)each behind rear windows
Partial Grill Block with Custom Air Scoop and 3" Open Catback Exhaust
Lambretta UNO150cc 4 Stroke Scooter
I need to clarify my earlier post. The only way that higher octane would improve your FE would be if your car has a knock sensor and is detecting detonation. As DarbyWalters mentioned, the only reason to use higher than 87(if that's what your car calls for) is if you have pinging on 87 in which case you likely have carbon deposits that need cleaning out.
Horsepower is how hard you hit the wall, torque is how much of the wall you take with you.
Save your money and just go with OEM plugs, jack up the air in the tires, switch to 0-20 synthetic oil AND.....drum roll please........GET A SCANGAUGE!
IMO opinion the Scangauge is the best mod you can do as it will help you modify the one thing that most people overlook when making mileage mods ---- The Driver. You'll become fixated on your mileage. Try it and see.
I also went with the racing disc caps on my old Metro, but some people are opinionated about how they look. I love them though, and my opinion is the only one that counts - just kidding.
I decided to replace the spark plugs today (OEM as suggested), since the old ones were filthy, but after doing so, the car won't turn over.
I made a dummy move and didn't pay attention to which spark plug wires went where, so I have a feeling I have them in the wrong spot.
Even if you installed the new spark plugs in your ears [ ] the car should still turn over. Spark plugs only fire the cylinder, not turn the engine over. Something in your starting circuit is amiss...[battery, starter, solenoid, cables, ignition switch, wiring, etc.]
unstable bob gable
AMERICAN ROAD WARRIOR!