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Please, read the whole thing before passing judgment. I'm looking for a discussion here, not to plug any particular product or try to sway anybody to do anything any differently than they do.
I bought the truck with 67k on it. I've always ran 87 octane from where ever is cheap, because that 30 gallon tank hurts my wallet a lot more than my old mustang's 15 gallon tank. The whole time I've had the truck, it's had a stumble between 2500 rpms and around 4k at WOT or near WOT. Feels like misfires or the transmission slipping. I just drove it easy, and figured I'd change the plugs and COPS in a few months, and that would be that.
A few tanks ago, after reading about some snake oil with PEA in it, I thought I'd run a can with some good gas through it, just for the heck of it.
That tank of gas was IMMEDIATELY noticeably different. The truck idled smoother. Had more low end torque. At WOT, it ran GREAT! No stumble, no misfires. Mpgs went UP! It was like a totally different truck.
I know, I know. Placebo effect, driving habit different etc etc. Well, I thought that too, which is why I waited until I could run a few more tanks of regular gas through it before making this post. Just hear me out here....
Ok, tank of "hot" gas ran out (well not OUT, but 40mi to empty) and averaged 15.4 mpgs on the dash. Back to regular old 87, no snake oil. Normal day. That thank ran pretty much the same as the "hot" tank for the first hundred miles or so. Then I noticed my mpgs on the dash slowly dropping... a tenth here, a tenth there. I drive 40 miles round trip to work and back 5 days a week. All highway. Cruise 70-80 mph the whole way. And I'm getting LESS mileage? Nothing has changed from last week except gas.
Must be a fluke.
Pulling onto the freeway about 250 miles into this tank of gas, go WOT, low and behold......the stumble is back....
Run the regular tank out, and think "ok, I'll put a few gallons of the 93 back in it, run it through a couple paces, then switch back to 87 and try again..."
10 gallons of 93 in it, BAM.....totally different truck again. mpgs start creeping back up, power is back, stumble is gone.
10 gallons of 87 when the 93 ran out.....BAM, right back to crap mileage and stumbling....
So I ask you fine people......what gives? I've read in a few posts on this forum that there is no advantage to running one fuel over another (Top Tier fuels aside), and yet, I experienced DRASTIC differences between 87 and 93 from the same station over the course of about 3 and half weeks.
Is this indicative of some worn out plugs or something?
Do these 3v 5.4's have the "smart" knock sensors that advance timing until knock is detected like my '12 mustang had?
Anybody got anything? Like I said before, I'm just looking for a sane discussion here. I'll tell you what fuel and additives if it becomes relevant.
Last edited by ol'skool; 06-04-2015 at 09:52 PM.
Reason: Changed year model, just got off when I made this and missed a stroke
As far as I know, it's bone stock except for a drop in K&N that I installed. Whether or not the dude that owned it before me flashed with an SCT or similar, I have no clue. I wouldn't think somebody would trade a truck in without reflashing back to stock to save the tuner for sale afterwards. Would they?
Yeah I get crappy mileage when I run 87 as well, then once i stick anything higher in, it runs like a dream. Mine's a stock 5.4 with a cold air intake added on...
I too am skeptical, but I am now considering this test myself. I will try it out and see if it works for my performance. I have been noticing some subtle nuances.
For you though, it does sound like you might be onto something and you have now since pushed me over the edge to try something different.
I do know that my motorcycle runs better with higher octane.
When I first started this little experiment, I thought it was just crappy quality 87 from speedway or circle k or where ever. However, the next two times I used 87, alternating 93 in between....for science, I went to the exact same station that I got the 93 from. So far, without fail, 87 from anywhere (top tier or not) runs like crap, and gets around 2 mpgs less (according to the dash). Then with 93, not even counting the one tank that had snake oil in it, power is back, mpgs climb back up, and the truck runs like a dream.
If anybody is actually interested in this topic, over the next month or so, I'll compile some video and data and keep this thread updated with my findings.
I can understand and agree that a higher octane fuel will net better performance and perhaps extra MPG on a tankful, but will the money paid for the higher octane fuel be worth it?
In simple terms, will 87 octane, at a cheaper price per gallon, be cheaper to operate the truck with, or pay more per gallon with 91 or 93 octane to net a slightly higher MPG rating?
It may be based on how the truck is used (towing?) or its daily driving enviroment (highway or city).
I run 87 octane primarily in my 2006 with the 4.6 V8. If I tow my camper, I fill up with 93 octane to get its better performance capability; that's the only reason why I step up to 93 octane ocasionally.
Last edited by Mod (Ret.); 06-15-2015 at 05:02 AM.
I'm going to try this because you have me curious, although I just topped off my tank yesterday. So when it runs out, I'll fill it up with 93 and report back what happens. (04 4.6L)
Ok, I have done the math. I think that my logic makes sense on this. Comparing 87 octane to Premium.
Current price per gallon: $2.67 (87) vs $2.93 (93)
My current avg MPG is 12.4. On a 30 gallon tank, I should yield 372 miles. Cost to fill tank with 87 octane is $80.10. Cost to fill tank with 93 premium is $87.90 for a difference of $7.80 per tank of gas
If my MPG increases by the following, then I will see savings on the extra miles per tank divided by new avg MPG and multiply that by the cost of premium per gallon.
1 mpg improvement will yield 30 extra miles per tank / avg mpg of 13.4 = 2.24 * $2.93 = $6.56 for a loss of ($1.24) (6.56-7.80 diff of tank cost above)
1.5 mpg improvement will yield 45 extra miles per tank / avg mpg of 13.9 = 3.24 * $2.93 = $9.49 for a gain of $1.69
2 mpg improvement will yield 60 extra miles per tank / avg mpg of 14.4 = 4.17 * $2.93 = $12.21 for a gain of $4.41
2.5 mpg improvement will yield 75 extra miles per tank / avg mpg of 14.9 = 5.03 * $2.93 = $14.75 for a gain of $6.95
3 mpg improvement will yield 90 extra miles per tank / avg mpg of 15.4 = 5.84 * $2.93 = $17.12 for a gain of $9.32
These numbers are based on my current driving baseline habits with 87 octane. Based on what I am seeing, I think that if I yield anything above a 1 mpg improvement, then the higher premium gas price is a wash and might put a few dollars pay back in your wallet due to the frequency of fills each week/month.
Someone prove me wrong on my logic, but this seems logical to me.
06-04-2015, 04:18 PM
I'd like to talk about Fuel for a minute.
