I'm thinking of buying a Mercedes from an uncle,but he says the car REQUIRES premium gas. With gas prices so high I don't know if the purchase would be worth it. Does the premium gas really make that much of a difference? I'm also hearing higher octane gas burns slower. Is that true?
2006-11-25 06:33:10 · 5 answers · asked by Mic B 2 in Cars & Transportation ➔ Other - Cars & Transportation
The issue here is the amount of compression. The more the fuel (gas/air mix) is compressed, the hotter it gets. Normal compression is 8:1, if the engine compresses at 9:1 or more you need more stable fuel so it doesn't go off due to the heat of compression before the plug fires. The higher compression improves power and efficiency, but needs gas that ignites at a higher temperature. In years past this could be done by adding tetraethyl lead, and 10.5:1 compression was more common. Cheap gas costs less to refine but cooks off at a lower temperature/lower compression. One sign that the gas isn't good enough is a crackling sound during acceleration. That's the 'ping'. Another is when you turn the key off and the engine runs on, chuffing and chuffing. The gas is unstable enough that compression in a hot engine is enough to fire, it doesn't need a spark. You won't notice this in an injected engine because the injectors shut off the gas. You may if it's carbureted.
2006-11-25 08:43:58 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Check the manual for the car. If not available, call a dealer. It may or may not. I had a plain ordinary Chevrolet that wouldn't run well on regular after I milled the heads down a little. It would buck, and the mileage was atrocious. It didn't require straight premium, but I would do one fill premium, fill regular at the 1/4 mark, again premium at the 1/4 mark, or mid-grade at the stations that carried it. It ran great on that blend for many years. If the Mercedes can be tuned to run on regular, that is fine, but I wager your uncle has tried that already, and found it wasn't satisfactory. Hey, if you are worried about the cost of premium gas, maybe you should be buying Ford, not a Mercedes.
2006-11-25 07:01:45 · answer #2 · answered by Fred C 7 · 0⤊ 0⤋
Try running regular gas in the car, if the engine doesn't ping it's fine to use it. Only high performance engines require high octane. Higher octane does burn slower but not enough to really improve mileage. The slower burn prevents pre-ignition firing, that is the gas in the cylinder burns before the sparkplug ignites, thus the pinging.
2006-11-25 06:42:03 · answer #3 · answered by RON C 1 · 0⤊ 0⤋
if it needs it burn it , a set of pistons for this motor is worth many times the difference in fuel price , yes it burns " slower " by a millisecond or less, the pinging that is heard with inferior fuel is the fuel burning at the wrong rate , coming very close to exploding
2006-11-25 07:26:45 · answer #4 · answered by sterling m 6 · 0⤊ 0⤋
yes most of them do require premium gas. i also hear that they get more mileage too... if he were a nice uncle he would just give it to you (no offense)
2006-11-25 06:42:37 · answer #5 · answered by Anonymous 2 · 0⤊ 0⤋