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Wed Jan 04, 2006 3:10 pm

Any thoughts or recommendations re: using higher octane gas? I'm currently running 87-91 octane in my '74 (the 91 has a higher concentration of ethanol and is actually cheaper than the 87 [Midwest thing I guess... lots of corn around here = cheap ethanol])... haven't seen any problems with using the 91, but have heard the higher octane levels (like 93 or even higher via additives) can be harder on smaller engines (due to higher temps)... any thoughts?

Thanks!

Wed Jan 04, 2006 3:54 pm

There's no reason to run anything higher than the 87 octane on a stock engine. If you had a larger engine with higher CR, you would need a higher octane fuel.

Wed Jan 04, 2006 10:14 pm

if you are runnig a stock engine that year car , its factory compression was lowered from other prior model years... thus no need for higher cost fuel...unless it makes your wallet feel good''''

Thu Jan 05, 2006 8:57 am

Sounds good - as long as the 91 isn't creating any unseen damage in my stock motor I'll keep using it since it's cheaper than the 87. I haven't noticed much of a performance difference from the higher octane gas, so no need to go there. Thanks for the feedback.

Thu Jan 05, 2006 9:51 am

in what area of the U.S. do you live? and 91 octane is cheaper than 87 ?

Thu Jan 05, 2006 10:41 am

When traveling through the midwest, I always use the ethanol mix. It will also clean out the varnish in your tank/lines/carbs.

My father says you have to leave your emergency brake on 2 clicks to allow you to keep the car on the road when runningthe 10% ethanol mix. :P

Thu Jan 05, 2006 11:48 am

i'm feeling really dumb right now - when i got my bug it had a rebuilt stock engine, and ive been using premium gas (93) for two years, with the idea that better gas would be better on an engine over time, and that it burns cleaner, and thus ive felt better about not having a catalytic converter. so it's actually harder on my engine?! does it burn cleaner?

Thu Jan 05, 2006 12:22 pm

stlawrence wrote: i'm feeling really dumb right now - when i got my bug it had a rebuilt stock engine, and ive been using premium gas (93) for two years, with the idea that better gas would be better on an engine over time, and that it burns cleaner, and thus ive felt better about not having a catalytic converter. so it's actually harder on my engine?! does it burn cleaner?

I don't think it is really harder on your engine or burns any cleaner, just a waste of perfectly good money.

Thu Jan 05, 2006 12:49 pm

The higher octane fuel is actually harder to burn. The higher the octance the more resistant it is to detonation. That is the only advantage. As far as less pollution with 93 is backwards. To my understanding unless you have a car that requires high octane fuel due to a engine tuning it will actually not burn the fuel as well and in turn pollutes more.

Thu Jan 05, 2006 3:09 pm

I live in eastern Iowa. The mid-level gas (91) is the cheapest, followed by the 87 and 93, respectively. I often get into parts of western IL (just across the Mississippi) and occassionally I'll see the same there (i.e. mid-level is the cheapest). I guess the fact that there are major ethenol plants around here helps with the cost.

I hadn't heard that ethanol helped with cleaning the varnish (as Randy in Maine mentioned), but hey, if I've got to live with midwest winters (OK, so this year has been mild), I might as well benefit from the local fuel :o).

Thu Jan 05, 2006 3:33 pm

salukibug wrote: I live in eastern Iowa. The mid-level gas (91) is the cheapest, followed by the 87 and 93, respectively. I often get into parts of western IL (just across the Mississippi) and occassionally I'll see the same there (i.e. mid-level is the cheapest). I guess the fact that there are major ethenol plants around here helps with the cost.

I hadn't heard that ethanol helped with cleaning the varnish (as Randy in Maine mentioned), but hey, if I've got to live with midwest winters (OK, so this year has been mild), I might as well benefit from the local fuel :o).

The 91 is about 10¢ a gallon cheaper and it's 10% Ethenol. I've seen at least two stations here offer 90% Ethenol but I've never tried it and didn't see what the octane rating on it was nor how much it costs.

We never can have enough Iowans in here.

Thu Jan 05, 2006 3:39 pm

Well this Hawkeye (from Ames) is allergic to corn pollen and that is why I am doing "life without parole" here in the state of Maine.

You cannot use E-85 ethanol as your distributor is not capable of changing the timing on the go, so don't use that. That is just for FFV or Flexible Fuel Vehicles that were designed for that fuel.

Thu Jan 05, 2006 5:35 pm

actuly , all bio fuel has a much lower BTU rating than pump gas . its lower heat is not efficient as the lower rated 87 octane . also 93 octane burns at a slower rate than 87 pump gas. thus to be used in higher compresson engines.

Thu Jan 05, 2006 5:44 pm

also forgot to add, that using bio or alchol base fuel WILL corode metal , lines , neddles,floats. pumps, etc. i dont recemend using gasahol in air cooled older vw's unless retro-fited...

Thu Jan 05, 2006 9:21 pm

I've used ethanol-added gas for years in my bugs with no corrosion problems at all - the only problem I've noticed was a higher tendancy to vapor lock in my big-bore 40HP in my 62.

In Colorado, you have no choice but to use ethanol during the winter months, all fuel along the front range urban corridor has to "oxygenated", and ethanol is what they use for that now that MTBE is gone. I think their oxygenated ethanol mix is different than the stuff in the corn belt, as I've always noticed lower gas milage with the Colorado gas but never when I've used gasahol in Cornland. One of the gas stations here in Douglas sells ethanol gas, but Wyoming doesn't have any tax break like Iowa and Nebraska do so it's not any cheaper, plus all grades at that store have ethanol. Their regular is higher octane though - 86 instead of the normal 85 you see for regular at high altitude.

-Andy

Thu Jan 05, 2006 10:11 pm

my 73 is pretty close to stock; and I've noticed that while it runs fine on anything I get almost 5 mpg better on the freeway on 91 or better. I keep exact records tank by tank including the type for driving so its not my imagination, my 69 bus is an identical motor (I built both) and will overheat in the mountains on 87, now I did keep the vw head design. if your heads are hemi cut you'll run better on the low octane fuels.

Fri Jan 06, 2006 12:47 am

Just use what Volkswagen tells you to. If you use too low octane gas, you will eat it up and end up spending more(plus using lower octane will increase engine temp, which of course causes cooling trouble maybe but also creates more NOx!). My 69 bug takes 91, so idk if any other volks are different

Fri Jan 06, 2006 2:27 am

For that 69 bug, "what Volkswagen tells you to" if you read the owners manual or if there are any original decals on the car, was 91 octane.

However, that what that specification doesn't tell you, is that back then, that meant 91 RON. That's not the same number that is on the pumps in the USA these days. Today you see "R+M/2" (or AKI) - which is an average of the RON with the lower MON octane number. What this means, is you can drop around 4-5 points off of that 1969 factory specification and run 87 octane instead. That is, in the USA, there are many other countries that still use the RON specification.

-Andy

Fri Jan 06, 2006 2:49 am

nictator wrote: Just use what Volkswagen tells you to. If you use too low octane gas, you will eat it up and end up spending more(plus using lower octane will increase engine temp, which of course causes cooling trouble maybe but also creates more NOx!). My 69 bug takes 91, so idk if any other volks are different

This is flat out wrong. Your mileage won't be any different, your emissions won't be any different, your operating temp won't be any different.
VW specified the lowest octane available when your car was new. That same low octane at your local gas station today is equivalent.

The octane number is a measure of resistance to pre-ignition. Nothing else. Save your money and use cheap gas. Anyone that takes their totally stock Bug to the high octane pump is simply displaying their ignorance and wasting money.

Fri Jan 06, 2006 4:11 pm

I was having gas probs with my 74 super and I was told by some old lady that has a 74 super that her bug "prefers" the "expensive gas" and runs better. So for a while I was using the most expensive gas because i was having gas line problems and my bug wouldnt run in fourth and first really well without coughing and sputtering. Now are you telling me I shouldnt use that, or that there is really no difference?