Just bought a 2014 Spyder ST Limited. Owners manual states to use 91 octane gas. Here in Texas we have 87,89 or 93. I don't mind paying the extra $$ for higher octane gas but my concern is how "FRESH" is the higher octane fuel compared to 87 octane that everyone uses and it gets replaced at the stations more often. Would think that "FRESH" 87 octane would be better than "STALE" 89 or 93 octane. Any chance of engine damage using 87 ?? Please help !!
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GAS Octane
- Thread starter bvschupp
- Start date
bronzeflex42
Member
2012
I used 87 in mine for a few months and didn't notice any engine problems. I went to 93 octane and i did notice i was going to the gas station a little more before i started using the 93 octane gas. I'm not a mechanic and don't know much about the engines, but it seems that the 87 octane gas burn a little faster than the 93 octane gas to me. :dontknow:
I used 87 in mine for a few months and didn't notice any engine problems. I went to 93 octane and i did notice i was going to the gas station a little more before i started using the 93 octane gas. I'm not a mechanic and don't know much about the engines, but it seems that the 87 octane gas burn a little faster than the 93 octane gas to me. :dontknow:
Bob Denman
New member
:agree: The engines are designed to run optimally on the specified octane...
When I had my 2010 RT, with the 998; I noticed about a 2.5 mpg drop in economy when I ran 87, rather than the usual 93...
On my 1330-equipped 2014 RT; The mileage didn't drop, but I noticed a decrease in low, and mid-range roll-on power.
When I had my 2010 RT, with the 998; I noticed about a 2.5 mpg drop in economy when I ran 87, rather than the usual 93...
On my 1330-equipped 2014 RT; The mileage didn't drop, but I noticed a decrease in low, and mid-range roll-on power.
scooterexpress
New member
someone once told me the difference about octane and in small engines such as ours that using 91 or better octane burned hotter and cleaner than 87, 91+oct won't clogg the sparkplugs up with carbon as fast as lower octane does. i've been using 91+ all the time and i'm still on my orignal plugs on my 2011rts 20k+ haven't noticed any drop in performance or milage.
Not really. Higher octane burns slower and is less volatile....more controlled combustion. Lower octane burns quicker and is more unstable. It burns faster and slightly less complete.
bluestratos
New member
As already stated, our engines have knock sensors that automatically control the timing for ignition. If you use a lower octane fuel, timing is retarded to insure damaging knock does not take place but the end result is less fuel mirage. Some fuel suppliers add eve more detergents or additives to the high grade fuel but if you use a quality name (Shell, 76 etc. they have all the additives in the lower octane fuel already.
When timing is advanced, the mixture ignites sooner and creates more pressure(compression) before it hits top dead center. As it passes over center it has more energy stored and as result the piston pushes harder on the crankshaft. This equates to more power for the same volume of fuel but, if the fuel detonates instead of burning evenly the result is knock which can destroy the engines. Knock occurs when high compression heats the mix and it auto combusts all at once, more like an explosion than a progressive burn. Higher (more) octane raises the point at which auto combustion will occur so more timing can be used to maximize the energy potential.
In the early 70s Shell stations offered a special tune up that would allow the high compression engines to run on the less expensive lower octane fuels. They simply retarded the engines timing enough to prevent run on(a form of auto combustion) and pre-ignition. The trade off was significant less power and lower fuel milage but they did not advertise that part, lol.
Bottom line is that if you drive reasonably, use the highest octane you can, the cost is offset by the increased MPG and you get a bit more pony power. If you drive hard, you probably still want to use the premium grade to enjoy the horse power gain but your MPG will not off set the costs.
When timing is advanced, the mixture ignites sooner and creates more pressure(compression) before it hits top dead center. As it passes over center it has more energy stored and as result the piston pushes harder on the crankshaft. This equates to more power for the same volume of fuel but, if the fuel detonates instead of burning evenly the result is knock which can destroy the engines. Knock occurs when high compression heats the mix and it auto combusts all at once, more like an explosion than a progressive burn. Higher (more) octane raises the point at which auto combustion will occur so more timing can be used to maximize the energy potential.
In the early 70s Shell stations offered a special tune up that would allow the high compression engines to run on the less expensive lower octane fuels. They simply retarded the engines timing enough to prevent run on(a form of auto combustion) and pre-ignition. The trade off was significant less power and lower fuel milage but they did not advertise that part, lol.
Bottom line is that if you drive reasonably, use the highest octane you can, the cost is offset by the increased MPG and you get a bit more pony power. If you drive hard, you probably still want to use the premium grade to enjoy the horse power gain but your MPG will not off set the costs.
stillriding
happy old fart
My guess, and it's only a guess, is that there wouldn't be a stale factor. More cars, especially imports, are requiring higher octane.
Bob Denman
New member
The only control that you have over that, is to buy from a very busy source! :thumbup:
I'd only worry about the controllable variables, and let this one slide...
ARtraveler
R.I.P. Dwayne
Always have run the highest octane in my :ani29:'s. Here, it is 90. Whenever I have used less octane, the power on the :spyder2: seems to be a bit diminished.
My mileage has always been in the sweet spot that most others get.
I only worry about stale gas if I find myself in very remote places, which does not happen very often. I have had to decant gas a couple times from a large 500 gallon or so above ground tank on a 4 x 4 frame. Did not notice any issues, but added more gas to the tank as soon as I could.
My mileage has always been in the sweet spot that most others get.
I only worry about stale gas if I find myself in very remote places, which does not happen very often. I have had to decant gas a couple times from a large 500 gallon or so above ground tank on a 4 x 4 frame. Did not notice any issues, but added more gas to the tank as soon as I could.
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doctorlbug
New member
unleaded vs leaded
In my area there is a Mobile that offers a 89 octane unleaded "non-ethanol added", would this be better than unleaded with 10% ethanol 91 octane??
In my area there is a Mobile that offers a 89 octane unleaded "non-ethanol added", would this be better than unleaded with 10% ethanol 91 octane??
LEEB
New member
Filling up
One question I have for the forum panel: Most pumps where I live have all three grades of gas coming from a single hose at the pump. If I select 91 oct, anyone know approx. how much 'leftover' lower grade gas I may be getting when I follow someone at the pump that used 87 oct.? If I'm just topping off the tank, maybe 1 or 2 gallons, do I really get any 91 oct.?
One question I have for the forum panel: Most pumps where I live have all three grades of gas coming from a single hose at the pump. If I select 91 oct, anyone know approx. how much 'leftover' lower grade gas I may be getting when I follow someone at the pump that used 87 oct.? If I'm just topping off the tank, maybe 1 or 2 gallons, do I really get any 91 oct.?
Bob Denman
New member
That's why I always choose 93 octane juice for it... Any mixing of 87, is only going to lower the octane of the delivered fuel. I also wait until I'm down below a quarter of a tank for re-fueling; Most fill-ups are right around five gallons.
Chupaca
New member
Use the highest....
don't think your going to find much stale gas. Most of your expensive high performance cars run on that stuff. You will not hurt your engine running the lower octane. Most manuals specify their gas internationally where lower octane in other countries will damage your engines. Some manuals will state your can run lower octane if using the vehicle in the us or canada...:thumbup:
don't think your going to find much stale gas. Most of your expensive high performance cars run on that stuff. You will not hurt your engine running the lower octane. Most manuals specify their gas internationally where lower octane in other countries will damage your engines. Some manuals will state your can run lower octane if using the vehicle in the us or canada...:thumbup:
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