+1. perfect assessment. i don't know about the mtbe, but all the pumps around dallas say "contains ethanol". do some reading about knock limits of fuels. the higher the octane rating, the higher the knock limit. 89 will have a higher knock limit than 87, and 93 than 89, diesel much, much higher than 93, etc. three things determine the knock limit you need your fuel to have: ignition timing, compression (be it static compression ratio or boost level), and heat. lower octane fuels burn more quickly. on a stock engine that recommends 86 octane like my 03 600rr, you need to run 86 octane, or the closest thing you have to it (probably 87). the computer is tuned so that the spark comes just at the right time for this fuel to combust fully during the power stroke. if you advance your ignition timing, the combustion starts sooner, and you may benefit from a higher grade fuel. if you increase the compression ratio, the fuel will burn faster, and you will probably benefit from a higher grade fuel. if you're running high levels of boost, hopefully you've got a knock sensor, and you'd almost definitely benefit from a higher grade fuel. and if you're getting pinging and knock running 87 on your factory engine that recommends 86, you should probably check and see why you're getting pinging and knock, but in the mean time, you could benefit from a higher grade fuel. on my f150, which took 87 octane, the o2 sensor was fouled (HC and CO readings out the roof), and i got lots and lots of pinging under load when i ran anything less than 93 octane. so i ran 93 for a year and masked the problem, probably made it worse, and then replaced the o2 sensor and it fixed everything. all that to say, you're not doing yourself any favors by running a higher grade fuel "just to be safe". using that logic, you could run oils with moly additives "just to be safe". hey, why not? because the vehicle wasn't designed for that. unless you have any real reason to do otherwise, always run what the manual tells you.

 

Ive always heard to use what the manual calls for andwhen I looked into what my bike calls for Im pretty sure it calls for 91 octane. Could be wrong and ill double check tonight, but Im almost sure I read that...

 

I use 89 just to be safe

 

so i put 89 in there last night.. and today when i get above 6k and let off, it will blow white smoke out the exhaust.. what would cause this? its not thick.. but its deffinately noticeable... i filled up at a Valero(sp) if that has anything to do with it

 

by the manual--
piston oil ring worn
cylinders worn, cracked or scored
valve oil seal damaged
valve guide worn
engine oil level too high
head gasket broke between oil return and cylinder
clogged breather hose

i would do a compression check and monitor the cylinders..

 

****!!! not what i wanted to hear! damnit damnit damnit!
i have a manual, ill read up on it tomorrow while i do nothing at work..

and im guessing the majority of those problems are costly fixes... ****

 

brown smoke--
main jet clogged or too small
fuel flow insufficent
carb intake manifold loose
air cleaner poorly seated

black smoke-
air cleaner clogged
main jet too large or loose
choke stuck
fuel level too high--floats
inlet needle held off needle seat

 

i would say to ride that tank out and fill up somewhere else and see what happens... or add some sea foam or fuel treatment and see what happens.

 

Not meaning to thread jack........but I've noticed this lately. I like keeping track of my MPG, and I recently switched back over from Shell to Philips 66. I found that Shell (clear) gives me less gas milage than Philips 66 (yellowish color). I have no idea what makes it yellow in color, but it always seems that if I get a tank of yellow gas, I get better milage with no difference in performance.

Anyone else notice, or is this just me paying far too much attention to the little things.

 

you sure that's not urine? urine burns a lot cleaner and more efficiently, resulting in a slight power increase and notable increases in gas mileage. i've started brewing my own fuel lately - the yellower and cloudier it is, the higher the energy density, and the more efficiently your engine will run.

:P but seriously, i wonder what the difference is. i know a lot of gas station clerks and owners and stuff (i'm a vendor for autotrader so i chat with them), and i'm told that the "premium" gasolines (shell, chevron, et al) have detergent additives, and the cheaper gasolines (QT, racetrac, conoco phillips, et al) do not. i don't know if this is true or if it's all hype, but that could make a difference.