andrewmitch

For a 2005 V8....The manual says the engine is suited for 87 but for better performance to use 91. I have always used 93-94 but with the cost of gas I am thinking about switching to 87 for the Runner. What is the consensus out there?

NathanBERG

Here is a interesting read. http://www.usatoday.com/money/autos/...emiumgas_x.htm

andrewmitch

good read, thanks

my other car is a talon turbo that requires 91. i tried 87 or 89 once recently and i ran like hell

i think i can get away with 87 in the 4Runner but still not sure i am going to make the switch

NathanBERG

I would try to find an 89 at the lowest. But that's just me.
I also personally like chevron and most definitely don't use ARCO or some low ball station.

brandontrek

with a naturally aspirated engine 87 or 89 will do you just fine...my dad has a 04 jeep grand cherokee with the high output v8 and he has been using 87 for a year now with no advers affects. he claims it runs just as good. Due to the compression and turbo in your talon you don't want to run anything less than 91. all i have ever run in my cars is 87(i personally have never had a turbo'ed or s/c car) just my 2 cents

andrewmitch

Thanks for the input. Is there anything to filling up in the morning or that bunk?

noahrexion

its your decision, you can use 87 becuae you have a pretty sophisticated timing/knock settup that will allow it. I fyou want the MOST power and efficiency than use 91 octane cause there will be a difference...

N/A doesnt always mean 87 octane, its usually the motor design. Hence high C/R cars like to run high octan elike vettes, ferrari's, honda's... etc

98LimitedCustomized

93 or 94 octane is total overkill, we can't buy higher than 92 at the pumps around here (can get Cam2 110 octane and better at 1 special station... or go fill up at the airport on jet fuel!) As said above, unless it's high compression or forced induction you're wasting your money. That said, I typically put in 89-91 octane. With my intake I really do run better on 89 than 87, I can tell every time. What does 94 octane run in your part of the country compared to 87?

andrewmitch

CT no longer offers 94, so it is 93 now.

There is about a 40 cent difference. Something like 2.75 vs 2.35.

Sunoco is the only pump I know that offers 91; we have 3 in town. One of the stations offers Racing Fuel - something like 108 Octane for something like $6 a gallon. If gas kept going up the racing fuel would have been the better value. I put it in my Talon once a summer. Probably not much difference other than psycological.

I was going to go w/ the 91 but 93 is only like 3 cents a gallon more. I figured the 93 was the better value.

Does an engine get used to a high octane and would that make it difficult to downgrade down the road?

tc

We had many discussions about this in thermo in college...

Great article - they just kinda glossed over the important, scientific part though.

Compression ratio = power. Preignition (knock/ping) is bad (unless you have a diesel, then it's necessary LOL). Higher "octane rating" means more resistance to preignition. If you don't have the necessary compression ratio (generally with super- or turbo-charged engine) then this amounts to LESS energy extractable from the fuel.

Contrary to popular belief, you should always run the LOWEST octane rating that does not result in preignition. (Assuming increasing the compression ratio to accomodate the highest octane available is not possible)

Suposedly, filling up in the morning gets you slightly more fuel (by weight) because the fuel is at a lower temp, therefore weighing more per gallon. I can't imagine it's that much given normal day/night temperature swings...

outrages112

i have a friend who owns an oil company and a gas staion (big operation) he swears there is no difference between gas stations, it all comes in through the same place and then the individual companies buy it then charge what they need to, i.e. overhead and whatnot.

FilthyRich

my mom;s new 05 4R with 4.0l uses 87 and runs just fine with it. Anything else is just a waste of good cash

98LimitedCustomized

Each company does start with the same gas, but they have additives and detergents that are meant to help keep your engine clean, believe it or not. I do however know that gas "gets old" so I wonder if that's why the cheapo gas stations seem to have "crap gas"... my idea is that they buy it in HUGE quantities and get a discount from the refinery, but have it sitting in holding tanks longer than a place that buys less volume and moves it faster... just a theory.

TC- yeah I'm currently in the joys of thermodynamics... you probably STILL feel the pain. As far as getting more gas in the morning, I'd say 99% bogus. The tanks are thousands of gallons and are below ground, with gravel on top of them. Their temperature fluctuations are sure to be miniscule. But hey, why not fill up in the morning, you can grab a Crap-a-ccino while you're there!

cootees

I'm in the same boat. he stock 450cc's on my talon require premium to keep from clogging. I run 87 in my 4runner without any problems but I also only get fuel at a bp or shell. I have a schedule that I tend to stick too, running mid-grade and premium every other tank full. So it goes; 87-89-87-91 and starts over again.

brandontrek

good theory....never thought of it like that!...

andrewmitch

So we both have a Talon and Runner? Good combo.

MarkieMark

87 should do. i use to run 89 when the prices were cheaper. but now i run 87. 91 on the 300ZX-TT no doubt.

surf4runner

nice article. i have tried all grades in all cars and rarely noticed a diff, esp in MPG increase, only between brands (chevron vs arco). i do not have a turbo but in my high compression motors i did notice a diff, esp when using 108octance (used to work at an airport so i got all the residual from mobile transfers ~0.5g X 20 times)
all DD use 87 w/o any probs.

Roadtripr

I actually think the opposite. The cheap guys would sell there gas faster and have a better turnover. If I go to the local cheap station or costco there is always a line whereas the Shell next door has much fewer visitors.

I always run 87. No need to go higher if the engine does not require it, especially with our current gas prices.

cootees

That we do. I've actually got two talons a 95 TSi(fwd) and a 91 ESi with a 4g63t swap and just got rid of a 95 GS-t. I love those cars... I just needed something reliable to drive to work... which is where the 4runner came in.