To keep it short and simple, I just serviced the fuel system including adding octane booster of a to remain un-named brand. I noticed a significant jump in throttle response and fuel economy.
As often as possible I run shell or hess 93 octane fuel, however, all stations have 10% ethanol and I HAVE gotten into badly contaminated gas before.
At the fillup immediately following the fuel system service, I added nothing to the tank, and noticed an 8 mpg decrease in MPG, lost crispness in the throttle, and lack-luster performance. I drove out that tank, and changed stations for the next one, again, 93 octane, no additives. Same result. (Approx 18-20 mpg averaged between city and highway with no flogging on it)
The next fillup, I returned to the same station, and used the same fuel again, but this time added the booster. I saw a notable increase in mileage of about 2-3 mpg but no throttle response or power gains. I made sure car was loaded weight wise the same, in similar driving conditions. I was going to dismiss this as i just had a dirty fuel system prior to the initial service but I happened upon a vendor of some CAM 2 (110 octane) fuel.
I did some research here on prime, and purchased 5 gallons of this pricey funny colored stuff, and mixed it with 10 gallons of 93 from the previous gas station. I took great care to drive the car again as near to perfectly the same as I could muster and I was absolutely floored with the results. The car was -alive-. I've never felt the throttle that responsive. I monitored each and every single mile, and patiently awaited the soft amber glow of the low fuel light.
Here are the results:
Year: 1992
Mileage: 111,265
Gearbox: Manual
Average daily commute: 53 miles
Air filter: New oem
Oil: Royal purple 10-30
Exhaust: cat-back taitec GTLW
Max combined MPG average with 93 octane (10% ethanol) unleaded and no additives: 20mpg
Cost average to fill up with 15 gallons: $56.75
Max combined MPG average with 93 octane (10% ethanol) unleaded + unnamed additive: 22mpg
Cost average to fill up with 15 gallons + additive: $76.75
Max combined MPG average with 10 gallons 93 (10% ethanol) unleaded + 5 gallons 110 race fuel: 28-30 mpg I wish I could say it with more certainty, but its almost impossible to drive the car the way I do with the first two tests for the entire tank while it feels so much more responsive (and ive tried THREE TIMES)
Cost Average to fill tank: $81.83
My rough math works out to ~2-3$ more to run the race gas mixture on the low end of the spectrum assuming 300 miles to 15 gallons on pure 93 (10% ethanol) and 420 miles on 10 + 5 (~.19 /mile x 120 more miles). If I could drive the car the exact same, I reckon I could probably eek out that magic 30 mpg.
Now heres where you come in... I would've chosen the race gas mix based purely on the intoxicating effects, the mpg bump is just a bonus to me.
What my curious mind is begging to know, is how just 5 measly gallons of race fuel dilluted into 10 gallons of average joe 93 octane gas, netted me the additional two days (~120-150 miles) fuel economy all three times I tested it. My mind is blown.
As often as possible I run shell or hess 93 octane fuel, however, all stations have 10% ethanol and I HAVE gotten into badly contaminated gas before.
At the fillup immediately following the fuel system service, I added nothing to the tank, and noticed an 8 mpg decrease in MPG, lost crispness in the throttle, and lack-luster performance. I drove out that tank, and changed stations for the next one, again, 93 octane, no additives. Same result. (Approx 18-20 mpg averaged between city and highway with no flogging on it)
The next fillup, I returned to the same station, and used the same fuel again, but this time added the booster. I saw a notable increase in mileage of about 2-3 mpg but no throttle response or power gains. I made sure car was loaded weight wise the same, in similar driving conditions. I was going to dismiss this as i just had a dirty fuel system prior to the initial service but I happened upon a vendor of some CAM 2 (110 octane) fuel.
I did some research here on prime, and purchased 5 gallons of this pricey funny colored stuff, and mixed it with 10 gallons of 93 from the previous gas station. I took great care to drive the car again as near to perfectly the same as I could muster and I was absolutely floored with the results. The car was -alive-. I've never felt the throttle that responsive. I monitored each and every single mile, and patiently awaited the soft amber glow of the low fuel light.
Here are the results:
Year: 1992
Mileage: 111,265
Gearbox: Manual
Average daily commute: 53 miles
Air filter: New oem
Oil: Royal purple 10-30
Exhaust: cat-back taitec GTLW
Max combined MPG average with 93 octane (10% ethanol) unleaded and no additives: 20mpg
Cost average to fill up with 15 gallons: $56.75
Max combined MPG average with 93 octane (10% ethanol) unleaded + unnamed additive: 22mpg
Cost average to fill up with 15 gallons + additive: $76.75
Max combined MPG average with 10 gallons 93 (10% ethanol) unleaded + 5 gallons 110 race fuel: 28-30 mpg I wish I could say it with more certainty, but its almost impossible to drive the car the way I do with the first two tests for the entire tank while it feels so much more responsive (and ive tried THREE TIMES)
Cost Average to fill tank: $81.83
My rough math works out to ~2-3$ more to run the race gas mixture on the low end of the spectrum assuming 300 miles to 15 gallons on pure 93 (10% ethanol) and 420 miles on 10 + 5 (~.19 /mile x 120 more miles). If I could drive the car the exact same, I reckon I could probably eek out that magic 30 mpg.
Now heres where you come in... I would've chosen the race gas mix based purely on the intoxicating effects, the mpg bump is just a bonus to me.
What my curious mind is begging to know, is how just 5 measly gallons of race fuel dilluted into 10 gallons of average joe 93 octane gas, netted me the additional two days (~120-150 miles) fuel economy all three times I tested it. My mind is blown.