High gas prices..how about regular?

[aldo1123]

Anybody think it's ok to put regular in a 4.4i X5 since gas prices are going higher and higher?

[albertax5]

i tried 2 tanks in my 06 4.4.seemed to run the same but my in town fuel mileage went from 19-20mpg to 14-15 mpg.so the extra cost of the 91 and the drop in mpg with regular might balance itself out...we are paying about 5$ a gallon here in alberta..

[mrbmwx5]

Sell your x5 Lol

[HPIA4v2]

Originally Posted by albertax5

i tried 2 tanks in my 06 4.4.seemed to run the same but my in town fuel mileage went from 19-20mpg to 14-15 mpg.so the extra cost of the 91 and the drop in mpg with regular might balance itself out...we are paying about 5$ a gallon here in alberta..

I had a hunch it's a bad math to do so, when I switched to premium non-brand like Costco/Safeway for a month and loosing about 1mpg.

let see, say you loose 2mpg going from 16mpg to 14mpg from 87octane to 92 octane, but save the diff in price of $3.73 compare to $3.95 (Seattle price at the moment).

*** 2/16 x 100% is negative saving of 12.5%, negative saving since you loose mileage

*** ($3.95-$3.73)/$3.95 yield a positive saving of 5.9%


So it doesn't save money to switch from 92 to 87 unless you:
1) don't loose mileage (wonder if it's even possible if you drive like grandma?)
2) price of gas goes down to $1.5.

[mrbmwx5]

Some tips on how to save gas for your rides.
Eat vegetable to lose weight
Remove all seats in the car to save weight
Drive like grandma
There a lot more but i forgot.....

[4MoJoe]

I switched 4 tanks ago to regular. I actually am getting better mileage. And I can't explain it. We went on a 600 mile round trip drive this last weekend, I computed my mileage and it was 26mpg for freeway. I was kind of blown away. I asked at the station I go to and they use 10% ethanol in the Premium but not in the Regular...

[aldo1123]

does using regular in the 8 cylinder do any actual engine damage or does it just affect mpg and performance?

[HPIA4v2]

Originally Posted by aldo1123

does using regular in the 8 cylinder do any actual engine damage or does it just affect mpg and performance?

Doubt it'll ruin it but as I've shown if you loose mileage you are not saving money. BTW, I think you need to compare mileage for about a month to make sure not just one fill of tank too many variables.

My friend uses mid-grade on his Toureg V8 for many years, his problem is not engine but control arm and brakes so my guess it's OK to use lower than 91 octane.

As far as freeway mileage, it's not good indication. 16-wheeler semis with 1000HP pulling 72000lb trailer can achieve 8mpg on freeway, put that semi in stop-and-go for a month, it'll melt your credit card at the pump easy.

[JCL]

Running 87 AKI doesn't do any damage. Neither does running 89 AKI.

You MAY lose power and mileage. You may not. It depends entirely on your local fuel. Fuel varies so much across North America in terms of quality that it is impossible to take another reference for your local conditions, unless that driver is using the same pumps you are.

My best mileage ever on my X5 was with 89. No loss of power.

Only way to know if the timing is being retarded is to try a full tank or two, and measure your mileage carefully. If it doesn't lose any mileage, go ahead and keep using it. If you notice a difference, decide if the penalty is worth it.

[o. l. t.]

Japanese cars run like crap on 87 (high compression VVTI engines), but the German cars seem to not skip a beat. All my Germans have ran like a top on 87.