bluestang2go

1. Hi all. Just got mine this week and even though the owner's manual says to run the car with 87 octane gas, I was wondering if there would be a difference in efficiency if I decided to use 94 octane on my bone stock stang.

2. Again the owner's manual says you have to use 5-W20 engine oil... It seems pretty thin to me for hot summer days. Once the car has been broken in good (10,000km), I intend to switch to synthetic. Which viscosity should I use?

Thanks everyone.

holderca1

1. Use 87 octane unless you get a tune specific to a higher octane.

2. Use 5W-20.

bluestang2go

Thanks holderca1. I appreciate it.

My Blue Heaven

Either MM&FF or 5.0 Mustangs reported a HP increase just by using 91 Octane without a tune. I say use whatever you can afford.

2005MustangGT

there is another forum post about the octane in the gas....guess what, you get what you pay for....sounds crazy doesn't it???

farmerjohn

Stay with the 87, but use a high quality fuel. Using higher octane fuels will yield very little added performance without a retune to adjust timing and a/f mix. There's another thread regarding engines running rich and sooting up exhaust. Wonder if those driviers are using high octane fuel without a retune. Remember, higher octane values enable a fuel to resist pre-igntion and allow the a/f mix to burn longer in the combustion chamber. For that reason, a retune is needed.
John

S197 GT

I myself run 91. I don't have a tune yet, but I usually run 91. I ran 87 when I first bought it, only because my dealer paid for my gas for 2 months.

My Blue Heaven

AGAIN....
April 2005 5.0 Mustang & Super Fords magazine, page 121:
"Our final test was to try different fuels by pumping out what was left of the 91 octane, then trying regular 87 octane, followed by 104 octane unleaded racing gas. There's definitely power in moving from 87 to 91 octane as the engine management follows the knock sensor. At 2500 rpm the gain is 2.7 hp and 4500 rpm we saw the largest "octane gain," a healthy 5.7 hp and 7.5 lb-ft jump, followed by a slight tapering in the gain. At 6000 rpm, the difference was 2.7 hp, still in the 91 octane's favor. No doubt the '05 engine management/knock sensor is tuned to allow more ignition timing(increased octane cannot raise power by itself unless the engine had been detonating on lower octane fuel."

The found no gain in using 104 race gas, maybe because of the slower burn rate, they weren't sure.

This testing was done at the Kenne Bell labs on a car they bought to R&D their upcoming super charger.

The octane testing was independant of the other tests. Their BASELINE car, with 91 octane was putting out 279.78hp @5200, and 301.46 ft-lbs tq @4400.

With an SCT tune, no HC/trap and 91o they got 287.54hp @ 5500 and 307.78tq @4300.

So, according to Kenne Bell, and 5.0 Mustang Magazine if you want more HP, use 91o gas.

Like I said before. Use what you can afford.

MJC302

Hi bluemustang....try reading this link from the Boss registry. I know it's long winded but it's informative about oil.

BossOil

I also have a problem with 5W-20 in a V-8. I'll be using 5W-30 Mobil 1 in the winter and 10W-30 in the summer once I hit ~750 miles on the odometer.

I agree with others on using higher octane fuel. It allows your engine to be capable of handling more timing, higher compression ratios etc. If you're going to drive your baby hard I would use a higher octane. If you're going to putz down the hi-way use the 87. Good luck!!

bluestang2go

Thanks pal this was very educating.
John

PONY XPRESS

I've raced with NEO 0-5W for years. Engines with power over 650hp. The lighter the oil the more power you make. Plain & simply.

Use 0-20w or 5-20w Mobil 1 for the street.

S197 GT

There you have it guys. I live in CA with the infamous $2.45 91 octane gas. I will still only run 91. And for just $2.00 more with each fill up for 5 HP, isn't that worth it to you???

05windveilbluegt

I can't find 91 anywhere locally will it hurt to use 93?

porsche

the higher the oct # the better!!!!

acadian

I also can't get 91 octane... just 87, 89 and 93. At least at the good gas staitions like Chevron and Shell which is the only places I will go. I used 87 octane until I got my SCT tune, which was a 93 octane tune. Now I use 93. If you can't find 91, get a 93 octane tune.

mmoonshot

87 octane will run fine stock, run her to 10000 mi then switch you're oil to mobil 1 full synthetic, this will cost a little more when you change the oil, but it is well worth the extra change I have owned several cars and trucks that have run over 250 K with no engine problems..

acadian

And Scott, you change your oil every 3k?

mmoonshot

Actually, I dont use mileage, Personally I use time, what I mean is I change my oil every three months no matter what the mileage is, I have found this to work nicely for me.

acadian

That sounds like a plan. How much do you drive though, if you had to take a guess? Do you think you average close to a thousand miles a month?

mmoonshot

Lets see, right now probably around 700 give or take a hundred.