Are there any differences among 87, 89, and 91 ? My car owner manual suggests me to use 91 but my friends said I can use 87 as well. What do you think?
2006-09-28 18:55:38 · 10 answers · asked by cac l 1 in Cars & Transportation ➔ Maintenance & Repairs
The octane rating of a gasoline is a rating of its resistance to knocking. The higher the number, the greater the resistance. Knocking occurs when two flamefronts within the cylinder collide. It can be very destructive of an engine. You can use low-test if you retard the ignition timing by a degree or two.
Two bad things can happen in the cylinder of an engine. One is pre-ignition. Pre-ignition occurs when the fuel ignites before the sparkplug fires it. This can happen because there is hot, glowing carbon deposits on the head of the piston from crappy gas or a poor fuel mixture. The deposits actually cause the gas to ignite and force the piston down when it really wants to go up. Very bad on bearings, con rods and other rotating parts.
The other bad thing is detonation, which is the actual explosion of the gas. Gas is designed to burn very rapidly. It starts to burn at the sparkplug and travels across the top of the piston in about 7/1000 of a second. Detonation is when the gas explodes because the compression ratio is too high and the octane rating of the gas is too low for the engine. In the '60s, you could buy 100 octane leaded gas for your hotrod with its 11:1 compression ratio and never hear a knock or a ping. The environmentalist wackos and nanny-staters took all that goodness away from us, however...
2006-09-28 19:03:57 · answer #1 · answered by christopher s 5 · 0⤊ 0⤋
It would help if you had stated what type of vehicle you own and the engine size. Yes, there is a difference between octaines. 87 is the lowest, for small, low horsepower engines, 89 is a midgrade octaine for average sized cars and medium size engines, and 91 is the high octaine for higher horsepower engines. If your manual calls for 91 octaine you had better use it or you'll get a spark knock upon acceleration which isn't good for your engine and will also give your engine more power with the 91. good luck mechanic for 30 years
2006-09-29 02:06:40 · answer #2 · answered by Anonymous · 0⤊ 0⤋
that depends on your car. some engines were designed specifically for premuim (91). But generally, running a lower octane fuel won't damage anything, and saves some money as well.
2006-09-29 02:05:33 · answer #3 · answered by smalldogmotorcycles 3 · 1⤊ 0⤋
Try it. If your engine sounds rough or you get less mpg go back to 91.
2006-09-29 02:04:34 · answer #4 · answered by Robert A 5 · 0⤊ 0⤋
Use what the manual says. Your friends are pretty dumb to tell you this. Yeah, it will run, but it will also eventually ruin your engine due to preignition due to compression of fuel/air mixture. Do you want that? That's what a "knock" is.
Next time, tell us what kind of car this is!
2006-09-29 04:20:35 · answer #5 · answered by MrZ 6 · 0⤊ 1⤋
you should use better 91 cause its stronger,powerful,and its cleaner for your car because it has more ethanol..so better use 91.i know it costs more!!!!
2006-09-30 18:41:45 · answer #6 · answered by Anonymous · 0⤊ 0⤋
Owner's manual was made for a reason...follow it.
2006-09-29 02:03:27 · answer #7 · answered by patient X 3 · 0⤊ 0⤋
use what manufacturer recommends. your engine probably has a knock sensor and will retard the timing if you use a lower octane. performance and fuel economy will suffer.
2006-09-29 02:19:08 · answer #8 · answered by Anonymous · 1⤊ 0⤋
I think you should use the one that the car manuel says but you should ask your mechanic. They know for sure.
2006-09-29 02:04:11 · answer #9 · answered by Melody 4 · 0⤊ 0⤋
more purified as the number goes up ...........does not make any diff i guess coz u need to change ur oil filter in every service ..rest upto u ...
2006-09-29 02:03:26 · answer #10 · answered by sid 2 · 0⤊ 1⤋