Regular verses high Test

[gpscotty]

I have the Ford 3 vavle V10 in our 08 Southwind and was wondering if anyone has found a milage or performance differance using different grades or brands of fuel. Any increase in eather would be nice. If never ask, you don't get answers.

[Mr_D]

Even the manufacturers say there is no reason to run any higher octane than the engine is designed to UNLESS you've modified it.

[mr300ce]

They may say that, but I only buy Chevron, unless not around, then only another 'name' brand. I always buy mid-grade for my mercedes, bounder, and even nissan pickup with 4cyl.

They always run great. No matter what some "desk-jockey" claims, I've seen engines torn down that have LOTS of deposits on the valves, pistons, cylinders, etc. (I manage a busy auto repair shop).

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[VanDiemen23]

Brands YES - for the detergent/additive content. It does make a difference in engine deposits over the long haul, but you probably don't need to use it all the time. Octane - NO. If you don't have the CR or ignition advance that requires higher octane you are throwing money away. Occasionally a higher mileage engine at heavy load and high temp will start to ping a bit on regular gas and the ignition system should retard spark to stop it. If you were using mid-grade fuel it might not have to retard but for the 99.999% of the time it wasn't in this condition you'd still be throwing money away.

[Fiesta48]

Octane levels above regular ( mid and premium) burn cooler to prevent ignition knock so they get less MPG's. Contrary to most peoples thinking.
If your engine requires higher grades it will get less MPG if regular is used because the timing is reduced, therefore reducing power. I had a Corvette that did.
And I buy anyone's gas. It all comes thru the same gas pipelines. Some different additives are added just before going to the pump.
BUT most important is to NOT buy gas where the under ground tanks are being filled by a truck tanker which stirs up the water and gets in your gas tank.

[radams]

The only difference I know of is that ethanol blends don't have the same energy value as straight gasoline so you won't do as well on the mileage.

[Ramblin]

Quote:

Originally Posted by radams The only difference I know of is that ethanol blends don't have the same energy value as straight gasoline so you won't do as well on the mileage.

True, and fuel with ethanol in it will degrade and gum up the works in engines where it sits unused for periods of time; lawnmowers, boats, etc. I never use ethanol in small engines for this reason. I don't know if fuel stabilizers like Sta-Bil do anything for biofuel (ethanol) degradation.

[RJay]

I had a similar question several years ago. I had a fairly long commute, a little over 100 miles round trip, so I decided to determine if I would be better off using 89 octane vs regular(no ethanol). I kept very accurate records for a month using regular fuel and then switched to 89 octane for another month. My driving habits were almost identical with mostly highway driving. I found I got better gas mileage with the 89 octane but the cost per mile was higher. So don't be fooled with the higher gas mileage you may get from using the higher octane because it may not be economical in the long run.

[donandmax]

Quote:

Originally Posted by Fiesta48 Octane levels above regular ( mid and premium) burn cooler to prevent ignition knock so they get less MPG's. Contrary to most peoples thinking. If your engine requires higher grades it will get less MPG if regular is used because the timing is reduced, therefore reducing power. I had a Corvette that did. And I buy anyone's gas. It all comes thru the same gas pipelines. Some different additives are added just before going to the pump. BUT most important is to NOT buy gas where the under ground tanks are being filled by a truck tanker which stirs up the water and gets in your gas tank.

How else are these tanks going to get filled except by a truck tanker Ive never seen anything else used for filling tanks..

[Campingman]

I know he meant while the truck was filling the tanks. I am a former Tanker Transport driver.

[donandmax]

Quote:

Originally Posted by Campingman I know he meant while the truck was filling the tanks. I am a former Tanker Transport driver.

Looks like I might have misunderstood him, my bad...

[Tha_Rooster]

I had a v10 put cheap it's not going to justify the cost difference. But I do put high test in the Bmers.

[mr300ce]

Ok....So, Helping my daughter move, I had to drive over the mtns from Lancaster, Ca (high desert, 2400 ft elevation) down to Pasedena, Ca
about 10 trips. 68 miles one way. 136 miles round trip.

1985 Nissan Kingcab 4x4 with 2.4L 5sp stick, with camper shell. Runs great, and perfectly tuned. Wind resistence same each trip.


It took about 3/4 tank per trip, so had to fill up every round trip, so I kept a record of my mileage. Speedo is dead-on acurate.

4 trips down with load, then back up empty, using Chevron regular gas. I always buy my gas at one particular Chevron station.

Got 17mpg every time.

I thought: "hey, this is a good time to try med-grade to see if there is any difference. So.....

Next 6 trips, med-grade gas (10 cents per gal more)....
Got 19mpg. Consistantly.

Used 8 gals per trip with regular gas at 17 mpg.

Used 7.15 gals per trip using med-grade gas at 19 mpg. (I have the receipts).

8 gals per trip at $0.10 more per gal for med-grade = $0.80


Per round trip I saved 0.85 gal. = about 8/10 gal. = $3.23 saved at $3.80 per gal regular.

Ever since then....I buy med-grade.

From Lancaster, Ca to Jacksonville, Fla is 2436 miles.

At 8 miles per gallon, that's 304 gal of gas using regular gas.

At 9 miles per gallon, that's 270 gal of gas using med-grade gas.

That's a savings of 34 gallons of gas.
If regular gas is $3.80 gal = $1155.00
Med-grade at $3.90 gal = $1053.00 Save $102.00 to get to Jacksonville.

PLUS....med-grade probably burns better in the engine.

I buy Med-grade.

[ottffss]

Quote:

Originally Posted by Fiesta48 Octane levels above regular ( mid and premium) burn cooler to prevent ignition knock....

They actually burn SLOWER to reduce knock, not cooler.