stale gas

[denniswheat1]

OK, l have been getting between 36mpg to 40 mpg on my 14RTs around my local area. Went on a1250 mile ride to hells canyon the other week with mpg from 35 to 46mpg. I bought some gas additive to add to tank. I buy premium gas all the time, but some of the little towns l probably bought from had stale gas? To make my point when l forgot to add additive l got 36mpg with additive 46mpg. Figured stale premium gas was the culprit anybody else notice the difference. Of course most stations probably sell lots of premium so no bad gas?? Dennis

[Bob Denman]

That's a distinct possibility...
They suggest1 octane, so I use the 93, that is commonly available around here...
Does the fuel in your area contain ethanol?
I've been reluctant to add anything to the fuel***, because I seem to remember a warning about that in the manual.


***Other than fuel stabilizer at Season's end...

[sledmaster]

For continuous use something like an ethanol neutralizer or carbon cleaner is better than a stabilizer-only product. Specifically, two of the best we have tested are from Yamaha, Fuel Med RX and Engine Med RX. Fuel Med is an ethanol neutralizer & stabilizer product, Engine Med has the ethanol neutralizer plus some of their carbon cleaner (no stabilizer). I have used CASES of this stuff in bikes and sleds and mowers and PWC and anything with an engine. I only use stabilizer (Fuel Med) when the gas is going to sit for 30+ days.

That said, you shouldn't see that much of a difference in MPG like what you did, sounds goofy. You must have had some really stale fuel to pull it down that far.

[denniswheat1]

We have ethanol based fuel here so that's bad to start with. I took off my cat.converter so was hopeing for better mileage, didn't get it so thought l try fuel treatment. Used Startron Enzyme fuel treatment and it made a difference. From 36 mpg low to 46mpg high. I find it hard to believe also, checked my figures many times. This was on back roads cruisein about 60 mph. Will try to stay away from small stations in small towns l guess?

[Chupaca]

wish it were that easy for me...I can have those differences without any additives but just on the variables such as when, where, how and weather. We can normally get 91 octane with ethanol so I run seafoam every few tank fulls to keep thing clean And close to optimum.. that and when we are feeling extra frisky we but a tank of racing fuel for an extra spirited ryde...

[sledmaster]

I do not believe the ignition timing will be advanced any further than what you would experience from 91-92-93 octane fuel, so anything in excess of this is a waste. With the knock sensor technology, the engine will automatically adjust ignition timing and fuel delivery for the maximum power, and pull it back as needed to resist detonation.

It is not uncommon for smaller low traffic fuel stations to have a tank of premium that is older than 30 days, and with any oxygenated fuel that can lead to stale fuel, excessive water content, poor combustion, etc. So if you must take fuel at a remote location you have to weigh the risks of getting (older) higher octane fuel or the (fresher) low octane fuel. That is a good time to be putting some additive into the fuel, for sure.

[denniswheat1]

OK! Thanks for comments, thought my bike was going gunnybag for awhile but believe now it's the type of fuel I'm buying so will save fuel treatment for backwater fuel ups. Thanks again guys!! Dennis

[IdahoMtnSpyder]

Based on my experience mpg comparison tank to tank is like jumping on a trampoline, up and down. There are too many variables involved including speed, hills, how full you get the tank, and so on, to say with any certainty that your apparent mpg from one tank is indicative of your average. I don't place stock in an mpg number based on anything less than about 10 fill ups.

[denniswheat1]

Based on my experience mpg comparison tank to tank is like jumping on a trampoline, up and down. There are too many variables involved including speed, hills, how full you get the tank, and so on, to say with any certainty that your apparent mpg from one tank is indicative of your average. I don't place stock in an mpg number based on anything less than about 10 fill ups.

Well guess what after 8000 miles on spyder l have fueled up quite a few times. This average wasn't based on one tank of fuel. My concern was why the average changed so much on each fill up, my rideing stile is the same and l fill up tank the same way each time. So why the big difference between tanks?? Well l believe it's stale gas. I don't believe stations sell that much premium anymore with these new smaller cars. I don't in wife's Malibu. Just my opinion!

[900Dave]

Stale/or separated meaning the gas and ethanol has separated and you may have pumped in a much higher concentration of ethanol than you think. The last time this happened to me the engine would stutter and did not want to excelerate. At 1/2 tank I topped off with 87 octane because it is usually the freshest. Then I refilled with 92/93 when that tank was empty.

FYI, some 87 octane here and there will not hurt the engine. Although I only use it when I have to.

[Gray Ghost]

ethanol starts to separate from the gasoline within 2 weeks to 90 days after being added. And if the tanks have any water from condensation, etc, the ethanol will separate from the gas and bond with the water. Since ethanol adds about 4 points to the octane rating, using old premium is not a bargain. Of course if the pump you are at uses just one hose for all grades you are getting a good dose of the lower octane stuff anyway.