XM23 wrote:The oil companies do their customers a serious dis-service by using labels such as "Premium" and "Hi-Grade" for their higher octane gasolines.
As everyone here knows (or should know), there's nothing "premium" about higher octane. It is required for some engines with higher compression ratios, but is in no way better than lower octane gas for engines that don't require it. In fact, lower octane gasolines have a higher specific energy content than higher octanes do. Using anything other than the lowest octane that doesn't cause pinging is a waste of money and may even perform worse.
Many uninformed customers, seeing something labeled "premium", think it must be better than the lower octane equivalents, and end up paying more than they have to. Of course, the oil companies love this and aren't likely to change their labeling practices any time soon.
see glad i made this thread cause I didn't know that. I was just doing what my ma and pa told me
I put 93 in my bike, they told me to when I bought it and most the people I ride with use it too...soooo just call me lemming while I look for the nearest cliff
The normal 87 stuff (per manual) from a Shell, Esso or main oil company station, not those discount grocery store stations. Don't know if this is true but was told they just buy their gas from the cheapest supplier and the refining process can have quality control issues. And with the rising gas prices, was told the higher grade stuff sits around longer in their tanks so I've stopped using that stuff for the car lately.
Intake temperatures can also affect what grade will work best. That's why most turbo vehicles are supposed to use higher octane even with relatively low compression ratios. Even intercooled turbos have higher than ambient intake temperatures.
Both my bike and my truck are supposed to run regular unleaded (86 octane or better), but in the summertime, when the weather bureau is recording 115 degrees F in the shade, temps are around 130 at my airbox. Both my car and bike will ping in the summer on 87 octane, so I bump it up to 89 octane mid-grade and it works fine.
Octane ratings for gasoline will also vary with altitude. in lower areas of the country, you'll find gas rangining from 88 to 93 octane, whereas high elevation pumps may only go from 85.5 to 90.
Note : for all of you non-U.S. readers, octane is measured differently, depending on your country. We use R+M/2 (average of research and motor methods). I'm not sure about Canada, but I know that Europe uses a different method.
The Rebel runs fine on 87. The S50 runs well on 89. The spitfire with a 48cc chinese engine gets 92. The buzz of the little 2 stroke engine on 87 is just to much. 92 mellows it out a bit.
Maybe it me but it seems my ninja 250 starts better and runs cold better on higher octane 93, every once in a while ill run it out to the track to pick up some 105, it seems to make it run even smoother when cold, and i like the smell, but 6.00 a gallon turns me off.
