octane fluctuations

[pdw]

Any one else experiencing a real fluctuation in Octane ?

Don't know how else to put it ...

Hypermiling with this recently restored 93 Saturn Sl 5sp. .... can really tell the fills that just don't deliver well.

Our fuel prices dropped from $1.32 per litre last month ... to a new low of $0.87 this morning. To boot, our dollar had gone down in value about 20 cents in that same time vs US currency.

( Perhaps the sudden extra supply has the ability to affect quality in certain areas ? )

[Tomjones76]

In the USA, this is the time of year they start doping our gas with "low-emissions" winter formulations that have bad mileage characteristics.

[brick]

Can I assume from the units that you are in Canada? If so, do you guys also have ethanol diluting your gas? I doubt the difference is octane rating, specifically, but more likely energy content. Just about anywhere in the US I would blame it on ethanol. That, or the switch-over to "winter" fuel blends.

[pdw]

Thanks, .... "winter formulations" factor is one thing I have to consider

--sometimes even premium seems flatter but still always better than regular
--but now and again a regular batch really hits the low side in "energy content"

Yes, ethanol is here too (Niag Falls Ontario Canada) ... less energy for sure.

Those two are bigger contibutors to a downward change in power. There are a couple of stations locally that seem to be able to keep a fairly consistant premium very reliably, but then also that remains the most expensive gasoline around

[Aether glider]

I've noticed this with E-85. Some tanks are better than others.

[Jalen]

Its not just you. Lately I've noticed a huge drop in not only FE, but power as well. I don't have as much getup and go at lower RPMs and a severe lack of power when trying to get into traffic on the highway. It's much more noticable with a full car as well. I can only assume that it's been the switch over to winter RFG fuels, and the full increase in gas here to full E10 for "winter emissions".

If you're in a mountainous area at all, you probably have the same.

[Taliesin]

Originally Posted by Aether glider

I've noticed this with E-85. Some tanks are better than others.

The worst thing about E85 is that it can vary anywhere from 75 to 85% ethanol (and that's what they admit to on the pumps).

E85 is a bit backwards... The winter blend has more gas and less ethanol in it.

[pdw]

Taliesin; more actual gas would be good. (Sometimes wonder how our independant suppliers buy their fuel .... )

Originally Posted by brick

Can I assume from the units that you are in Canada? If so, do you guys also have ethanol diluting your gas? I doubt the difference is octane rating, specifically, but more likely energy content. Just about anywhere in the US I would blame it on ethanol. That, or the switch-over to "winter" fuel blends.

re "energy content "

Using the best premium around has recently shown hypermiling results that go the farthest on one dollar. Of course I don't fill the tank ever, ... just run tank-bottom/ least-weight.

( I get to thinking/believing out of experience that the premiums only at few/select pumps ensure the most energy out of each dollar without fail every time. It's those I'll be studying some more. )

[Taliesin]

Originally Posted by pdw

Taliesin; more actual gas would be good. (Sometimes wonder how our independant suppliers buy their fuel .... )

re "energy content "

Using the best premium around has recently shown hypermiling results that go the farthest on one dollar. Of course I don't fill the tank ever, ... just run tank-bottom/ least-weight.

( I get to thinking/believing out of experience that the premiums only at few/select pumps ensure the most energy out of each dollar without fail every time. It's those I'll be studying some more. )

In my case, more gas in my E85 is definately worse (and is the most premium fuel you can get with 105 octane).

Almost all of my driving in my E85 vehicle is towing 4000 pounds (these are my experiences so far with 1 1/2 years on the truck, and before hypermiling)...
Gas: 10 mpg
E85: 10 mpg (20% cheaper)
E75: 10 mpg (12% cheaper)

Which would you choose?

Now if they could only E85 availability up, we could drive vehicles that are fully designed for it and get excellent FE out of them (this includes raising the compression of the engines). However, then we wouldn't be able to call the FFV, since they couldn't use regular gas.

[pdw]

My 93 1.9litre Saturn with its longer stroke and great torque likely benefits from the extra energy of hightest at the lower rpms (1500-1800). Also, this vehicle barely tops 2100lbs when void of contents.

Cruising with the 4000lbs plus Ram-weight, your 4.7 sounds to be doing the same in all combinations ...

... perhaps, if running at higher revs ... could also be a distinction ?