What kind of Fuel / Oil are you using? [Archive]

DemonSVT

12-10-2002, 03:25 AM

Originally posted by: SLaPiNFuNK
alright...

Im wondering if opening up the engine by having intake / headers / exaust alla that will benifit from a higher octane fuel...

NO. Anyone that runs octane higher than 87 is only taking extra money from their wallet. Nothing else!

The PCM is programmed for 87 octane. Running higher octane then programmed for will actually decrease both performance & MPG. (less fuel is actually being burned because it has a higher flash point and the flame front is not starting or expanding soon enough)

The only reason to run a higher octane is if you are running forced induction, an aggressive chip, or nitrous (and it's only a bonus when the nitrous is actually flowing)

Some cars as they get older may require you to step up a grade of fuel to stop pinging. However this does not increase performance it just stops the pinging. (pre-ignition for carbon deposits)
Clean you intakes & have a professional Motor-vac/fuel injection cleaning done. Then go back to 87 octane.

SLaPiNFuNK

12-10-2002, 06:23 AM

That is what I was thinking and the response I was hoping to get...

AssassyN

12-10-2002, 09:27 AM

Originally posted by: DemonSVT

Originally posted by: SLaPiNFuNK
alright...

Im wondering if opening up the engine by having intake / headers / exaust alla that will benifit from a higher octane fuel...

NO. Anyone that runs octane higher than 87 is only taking extra money from their wallet. Nothing else!

The PCM is programmed for 87 octane. Running higher octane then programmed for will actually decrease both performance & MPG. (less fuel is actually being burned because it has a higher flash point and the flame front is not starting or expanding soon enough)

The only reason to run a higher octane is if you are running forced induction, an aggressive chip, or nitrous (and it's only a bonus when the nitrous is actually flowing)

Some cars as they get older may require you to step up a grade of fuel to stop pinging. However this does not increase performance it just stops the pinging. (pre-ignition for carbon deposits)
Clean you intakes & have a professional Motor-vac/fuel injection cleaning done. Then go back to 87 octane.

Really?! Wow that's something new to me...when I got her brand new I put mid-grade in on every fill up because the engine was new and I wanted to treat it good, but once I get past 1,500 miles (yes, I'm still under 1,500 miles...it's been in the garage for winter for over a month now :() I'll just use regular...thanks man!

Mity2

12-10-2002, 11:40 AM

i use 87 and Super synthech 5w-30. I put in 5w-20 by accident this past oil change, but due to very cold wheather we are getting
(anywhere from -1F to 5F) it actually kind a helps during start up.
puttong in 5w-30 next time tho

ArizonaCougar

12-10-2002, 07:35 PM

I completely agree with DemonSVT. Like many others, I was guilty of the "wanting to treat the new car well" by adding higher octane. All I did was spend more money than necessary. Period.

Fett

12-10-2002, 09:04 PM

DemonSVT, not questioning your logic...but I wonder if you have any insight into my "problem".

I have always had a pretty good understanding on fuel and octane levels, and I have never been fooled into believing that one is really "better" than the other. However, I did notice something that I can not understand. Mind you this is something that is consistant.

I always used 87, because that is what is recommended. Whenever I fill my car up, I fill until fuel pump shut off, and reset my trip, MPG, and avg speed settings. This way I could track how many miles I was getting out of a full tank, because I then drive until I am damn near empty. Usually around 5 miles to go, according to the questionably accurate readout. I consistantly got 280-290 out of a tank of gas, from day one. One day, for crapps and giggles, I filled up with 92(?), and went 330 on that one tank. So I reset and filled up with 87, went 285 or so, then went with a tank of 92, and back and forth and back and forth. Now I drive the same route everyday, 30 highway miles to and from work, same traffic, generally same conditions all around. Each tank of 92 would get me 330 or so, and each tank of 87 would get me 285 or so. Now that is a HUGE difference out of a 15 gallon tank. I am completly lost on this, I can not for the life of me figure out why such a huge difference in milage depending on the octane grade of the fuel.

Any thoughts?

Ziggo

12-10-2002, 09:22 PM

I don't know if you guys have noticed, but it seems like Mobil 1 5w-30 is being phased out. I see Mobil 1 synthetic 0w-30 and 0w-40 in its place. Any ideas?

Hmm....I'll do some reading.

SLaPiNFuNK

12-10-2002, 09:47 PM

what i have heard / noticed....

our engine / all engines are designed to handle a certain octane.... the engine is made to to burn fuel at a certain rate and higher octane fuel burns faster there for putting higher octane fule in a car that only uses 87 octane will actually decrease the cars performance and gas milage...

OIls is that im reaslly wondering about...

caenus

12-10-2002, 11:58 PM

I use Mobil 1 supersyn 5w-30 in summer and 5w-30 in winter (yeah well our winters are basically like summer anyway). I also use premium Shell which is 91 or 93 octane I believe. I have a diablo chip and ever since I got it I've been using premium gas. Since it advances timing, I didnt want to risk use medium or 87 octane gas. Since I put in this SVT uim/tb I've increased about 1.5-2 mpg on my "inaccurate" gauge. I'm at about 24mpg in traffic driving, some stop and go, mostly traffic light to traffic light driving. If this keeps up maybe in 2 years the SVT uim pays for itself in saved gas money, heh :)

Croc

12-12-2002, 05:18 PM

Fett that is an interesting observation that you made. I used to do the higher grade/octane every now and then and never noticed a difference like that. I may try that one day to see if there is a difference. I too reset everything when I fill up. An interesting fact my mother told me. She took this class at the local Chrysler dealer where she bought her car (PT Cruiser) and they told her not to use a higher grade/octane as the engine was not designed for it and may do more harm then good. I think he (a qualified mechanic) was referring to unburnt hydrocarbons going through the system.

As for the type of oil, I use 5W-30 but usually no particular brand. I use whatever is on sale, but not generic. My buddy and I usually change my oil. I do tend to sick with Fram oil filters though, no particular reason, I'm sure there are better ones out there.

Blackcoog

12-12-2002, 05:50 PM

93 or higher with my high compression and SVT ECU and I use Mobil 1 synthetic for oil.

MrFroge

12-12-2002, 10:59 PM

Well I have to put my 2 cents in .. I've been trying to find a difference between Shell low and high octane, other than price, but to no avail.. As for oil, I use AmsOil 0w30..

GrandMasterKhan

12-13-2002, 04:56 AM

I also use Amsoil 0w-30

i run 93 octane. when i ran 87 my car pings. my uncle (who has been selling fords for 20 years) says that Ford programs the ECU to adjust to which octane you use. i believe this is why FETT notice an increase in MPG with high octane. i have also noticed this. (i also have aem intake and svt uim/lim..if that matters)

PacmanTravis

12-13-2002, 01:55 PM

I use 91, just because I have the IAT Mod. When I go to the track I also add octane booster.

BrantlyJ

12-13-2002, 02:41 PM

Maybe I can share some insite on this. Being a motorcycle junkie I want nothing but the best for my scoot. My group and i have done many test on gasoline and oils.

First off high octane gas is a waste. Like someone already mentioned unless you have a high performance engine or mods you don't need it. Using a higher than normal octane gas does nothing but leave carbon deposits on your pistons and valves. Carbon deposits can build up enough to be a problem. Some of them are hot spots, decreased performance, engine knock, etc....

As for oil, most oils are decent. I personally run Synthetic. In my last car I ran 10w-30 in summer and 5w-30 in winter. Not sure what I'll run in the Cougar.

As far as oil filters, Someone mentioned Fram. They are the worst. There are actually lawsuits against Fram cause the filter destroied the engine. We cut open filters to compare construction. The only filter that had cardboard endcaps was the Fram. All the others used metal. Infact these were used filters and the cardboard ends were fraying. The filter was actually contaminating the oil more than it was filtering. Imagine having an oil port clogged by cardboard fibers. I recommend either Wix, or Hastings. Both can be bought at a local Napa or other auto parts store. I haven't cut open a motorcraft filter but the first time I change the Cougar I will.
I do have pics of the filters somewhere if anyone is interested.

just my .02 cents

Brant

lucky

12-15-2002, 09:42 PM

K&N makes a oil filter, have you done anything w/ that one?

BrantlyJ

12-15-2002, 09:55 PM

Lucky,

I don't think so but I will check. we were dealing with motorcycle filters here and don't believe K&N makes aa filter for our bikes.

I am willing to cut open and inspect any filters that anyone would be willing to send me. Send me a message if you have one.

Brant

Eminem

12-16-2002, 12:26 AM

We need someone on this board that actually designs and builds cougars perhaps they'll have the answers to this fuel grade debate. :biggrin: 8 mile...

BrantlyJ

12-16-2002, 12:51 AM

What's there to debate about fuel grades?? 87 octane is what to use, no if's ands or but's about it. high octane is for performance engines only. using it in an engine not desinged for hiogh octane will do more damage than good.

As for the person that got better milage with premium... the 87 octane probably had ethonal and the high octane didn't. It's a proven fact that ethonal fuels provide worse gas milage than no ethonal fuels. Also the sub-concense does wierd things. If you believe you'll get better mileage you'll drive different. You many not notice it but you do. Hell when I had my Olds Cutlass it usually got 15 mpg. When I really tried I was able to get 20 mpg. I didn't have to drive like a granny either

Brant

PacmanTravis

12-16-2002, 01:02 AM

Car And Driver asked the same question that we are asking....regular pr premium (http://www.caranddriver.com/xp/Caranddriver/features/2001/november/200111_feature_gasoline.xml?keywords=octane)

SLaPiNFuNK

12-16-2002, 01:49 AM

how often are you lot changing your oil?

im usually 5-6000 miles once ever 2 months...

GrandMasterKhan

12-16-2002, 02:36 AM

I have AMSOIL....rated to run 24000 miles between oil changes...and 12000 for filter changes

0w-30

i change my oil every 15000 as i run my car hard.

Blackcoog

12-16-2002, 03:33 AM

Wow an oil change every 15k miles?

SLaPiNFuNK

12-16-2002, 04:26 AM

should i switch to synthetic oil if i drive over 2500 miles amonth?

GrandMasterKhan

12-16-2002, 05:05 AM

if you switch to Amsoil synthetic you'll be able to go 24,000 miles between oil changes especially highway miles....meaning you'll SAVE alot of money. instead of changing your oil every month (2,500 a month is alot...highway miles i hope) thats what? 25 bucks a pop? thats 300 bucks a year....if you had amsoil you would only have to change it once a year or 24,000 miles...amsoils is about 50 bucks for 5 quarts..but it pays for itself and it makes your car run better and improves MPG.

don't believe me? check it out at the AMSOIL website AMSOIL 0w-30 high performance oil (http://www.amsoil.com/products/tso.html)

hes some more info about AMSOIL

normal oil max temp before evaporation: 250 degrees
engine operating temp: 250 degrees
amsoil max temp before evaporation: 400 degrees

slockin

12-16-2002, 12:06 PM

I just switched to the Mobil 1 SuperSyn 5w-30 and a K&N filter.

I had the same thing as Fett happen with my 99. If I put in 87, I'd get about 17 mpg. If I put in 93, I'd get almost 21. So, it was more economical to put in 93 for me. It was an ATX that ran mostly city miles (only 5 highway miles to work) and I always put in Mobil gas (mmmmm..... SpeedPass). Even tried resetting the computer, didn't change anything. :shrug:

-Nick

Wayne7497

12-16-2002, 03:49 PM

Fuel = BP Ultimate 98 Octane ( and yes Aussie ECU is different than US and Ford here recommend Higher Octane for the Cougar)

BP Ultimate 98 Octane (http://www.bp.com.au/products/fuels/bp_ultimate/ultimate.asp)

Oil= Shell Helix Ultra 5w - 40

Shell Helix Ultra (http://www.shell.com/home/Framework?siteId=au-en&FC1=&FC2=%2FLeftHandNav%3FLeftNavState%3D3%2C3%2C0&FC3=%2Fau-en%2Fhtml%2Fiwgen%2Fshell_for_motorists%2Foils_lub ricants%2Fhelixrange_0620.html&FC4=#1)

Rylee44

12-17-2002, 12:25 AM

i run 91 octane atleast... Im pretty sure thats what the SVT needs? I also use Valvoline 10w40 Synthetic oil...

GrandMasterKhan

12-17-2002, 02:23 AM

87 is recommended for a STOCK cougar. who here has a stock cougar? the more air you flow in/out of the motor the more power you make. i could only assume that a modified motor would obviously benefit from higher octane.

if you happend to read that article a few posts up you'll Clearly read that he Mustang and the Truck gained HP from higher octane. now imagine if that mustang had the typical I/E mods... if i rememeber correctly a mustang would proably gain about 30hp at LEAST. would it not also run better on 93 now that you've juiced the motor up a wee bit? or would you continue to pump 87 just because you lil book says so?

and please! what do Most dealers know about mods? well they hate em. and get this...my dealer said my WHOLE dash was aftermarket because of my kenwood cd player.

BrantlyJ

12-17-2002, 01:05 PM

I bet lots have a stock cougar. Not everyone has the money for mods or if they do have don't think modding is a priority. Personally I dump all my money in my cycle.

I did read the article and it also CLEARLY stated the increase was only 1-2 ponies. also one of the cars decreased in HP. It was also noted that there is slight percentage of error and that the increase and decreases fell within these percentages.

I agree doing intake and exhaust mods lets more air and fuel in. However it's not enough to require high octane. On my cycle (which has no fancy pantsy sensors) I did a free flowing ram air intake and free flowing exhaust. I increased the horsepower roughly 20% with just these two mods. By your theroy I should be using premium cause it would be knocking as hard as a Jahovah Witness. However it's not. Also I have seen a torn down motor that ran octane higher than nessasary. Hugh coating of carbon on the piston. I could proably get a pic if you want to see it.
Flowing more air dosen't require high octane. Increased compression, timing changes, new computer chip, etc... requires high octane.

BTW, I haven't even read my owners manual. I am the last person to tell you to do what a book does. I gather my info from personal experiance and advice from trusted, knowledgable people.

I'll admit, with cars, I'm still learning and I appricate all the help I've gotten here. Now bikes are different. I can rebuild a carb in my sleep :biggrin:
Anyways, use what you want, not my car, I won't have to scrap the carbon off the piston heads, or have the decreased performance that carbon build-up gives :wiggle:

Brant

Ziggo

12-17-2002, 01:20 PM

Originally posted by: BrantlyJ
By your theory, I should be using premium 'cause it would be knocking as hard as a Jehovah's Witness.

:rofl:

caenus

12-17-2002, 10:52 PM

So do the people with chips that advance timing and require the higher octane have this same problem with carbon deposits? I'm hoping no, because the chip advances the timing and allows the fuel to burn longer thus using the "excess" fuel that a stock cougar would build up. Anyone care to comment?

BrantlyJ

12-18-2002, 01:32 AM

Sure I'll answer that.

The higher the octane the slower it burns. With standard timing by time the stroke is finished there is still unburned fuel. This is what leaves the carbon deposits

changing the timing so it sparks earlier gives enough time for the fuel to burn completly there by reducing the chance of carbon build-up.

However I still run a can of Seafoam through the gas tank every oil change.

Brant

GrandMasterKhan

12-18-2002, 02:25 AM

i didnt say mods would make it ping. i said higher octane MIGHT help if your pushing more HP. and I DO notice increase in MPG when using 93 and my car doesnt ping when i use 93 as it did when i ran 87.

caenus

12-18-2002, 11:25 AM

...and what is seafoam?

BrantlyJ

12-18-2002, 03:02 PM

Seafoam is similar to Gum Out or other fuel system cleaners. I think it's vastly superior though. I can get it at most auto parts stores, All Napa's have it but they might have to order it for you.

Brant

caenus

12-18-2002, 05:46 PM

Figured it was similar, just never heard of it. Is it better then the other brands or do they all do about the same thing?

BrantlyJ

12-18-2002, 06:34 PM

dunno, never used anything else. All I know is that's it's used and recommended by just about everyone in my motorcycle group. And we are 10,000 strong. When that many people endorse a product I don't argue lol It does work though.

Brant

Eminem

12-21-2002, 01:06 PM

I put in a full tank of 87 octane and the car feels slugish and I can't get no where near the same mpg

MrFroge

12-21-2002, 01:57 PM

Ping in our near stock 2.5L is usually caused by the internal build-up of carbon deposits.. Some gasoline additives made for this purpose could slow or prevent the build-up of these deposits.. I have stayed with SHELL which is supposed to prevent this problem and at 65K, I don't have a problem..

dv6cougar

12-22-2002, 12:07 AM

93 octane fuel.. and 5w30 oil as the book says( only 01 and up have the 5w30 on the oil cap i think, maybe 00 too).... and i dont' use syntentic becuase I was told by a mechanic that if i started using it on a motor that was used to regular it would damage the engine

is that true?

caenus

12-22-2002, 12:05 PM

My manual (2000) says 5w30 for the oil, I believe the 01/02 use either 0w30 or 5w20 oil to help improve gas mileage. Either way it doesn't matter too much unless your car sees freezing temperatures, mine doesn't.

dv6cougar

12-22-2002, 12:10 PM

Originally posted by: caenus
My manual (2000) says 5w30 for the oil, I believe the 01/02 use either 0w30 or 5w20 oil to help improve gas mileage. Either way it doesn't matter too much unless your car sees freezing temperatures, mine doesn't.

mine does see freezing temperatures.... what oil should i be using then? it's a 99 with 90K

caenus

12-22-2002, 12:25 PM

I would put whatever is in your manual. I believe 0w30 has better properties for when you start your car in the cold, its a thinner oil. (I think).

dv6cougar

12-22-2002, 12:30 PM

ok cool, my manual i'm pretty sure says 5w30 and i've always used that in my cougar so i'll keep doing that :)

khusted

12-23-2002, 07:21 PM

I use 93 octane. One time I hit the wrong button at the pump and put in 87 instead. I noticed a huge difference in my mileage. I don't have exact numbers, but I had to fill up quite a bit sooner than usual. Also on the way to CF I was the only one in the caravan who used 93 and I got much better mileage than everyone else, but at the time I attributed it to mods.

As far as oil goes...I used 5w20 cuz that's what it says in the manual. It's very hard to find so I've taken it to the dealer that last 2 time (who knows if that's what they're using...I doubt it)

Seelow

12-24-2002, 12:15 AM

I also get better mileage with 93 then 87 usually about 2-3 miles/ gallon. It works for me and whats an extra few bucks at the pump. And for oil i use mobil1 5w-30 change that and filter every 3,000-3,500. I've always used fram but from what i read I might change.
Hey BrantlyJ Yo must be one of the harley folk. I know my bike needs 93 its a 12.8:1 compression stock. But thats must be the high performance un like yours. Just kidding with you I like all bikes, just cant afford a old man bike yet. No pun intended if you are one.

BrantlyJ

12-24-2002, 01:59 AM

just for the sake of seeing what you guys are talking about I'm gonna get a few tankfuls of 91 (highest we have in Des Moines) It goes against what I have learned about octane levels but maybe I didn't understand it completly. Or maybe what I learned only applies to less sophisticated systems such as bikes.

I DO NOT own a Harley and wouldn't take one if you paid me. I don't like Harley reliablity and hate the poser image that goes along with the name Harley. I do own a cruiser type, 2001 kawasaki Vulcan 800 Classic. I have it set up for touring. Put on 12,000 miles this last summer.

Brant

Seelow

12-24-2002, 02:48 AM

It never hurts to try new things :poke: Glad to hear u have a kawi I have a 00'zx6r myself.

Sinister

12-25-2002, 06:35 PM

mid grade fuel.... Mobil 1 Synthetic oil and oil filter 5W-30

Eminem

12-26-2002, 01:55 AM

tru I get crappy gas milagfe when I use 87 octane carbon build up or not

dv6cougar

12-26-2002, 02:08 AM

Originally posted by: Eminem
tru I get crappy gas milagfe when I use 87 octane carbon build up or not

ya i used it once, gas mileage was worse

gamiller

01-09-2003, 11:07 PM

i know i'm late to be posting, but TSB 02-1-9 states:

ISSUE
Ford Motor Company now recommends SAE 5W-20 viscosity grade for servicing most gasoline and flexible fueled vehicles.

ACTION
All 2001 and 2002 vehicles where SAE 5W-30 is specified should be serviced at the recommended oil change intervals using SAE 5W-20. This oil is an improved formulation to improve fuel economy.

Testing has validated this viscosity grade can be used in many previous model year vehicles. It is recommended ALL vehicles on the following Vehicle Application Listing be service with SAE 5W-20.

Veh. App. Listing Approved For SAE 5W-20 Motor Oil
* 1995-2000 2.0L Zetec Contour/Mystique
* 1999-2002 2.0L Cougar
* 1995-2000 2.5L Contour/Mystique
* 1999-2002 2.5L Cougar

EDIT: Corrected misprint by Ford. Thanks Mr. Froge and SlowTime!

MrFroge

01-10-2003, 04:34 AM

Originally posted by: gamiller
i know i'm late to be posting, but TSB 02-1-9 states:

ISSUE
Ford Motor Company now recommends SAE 5W-20 viscosity grade for servicing most gasoline and flexible fueled vehicles.

ACTION
All 2001 and 2002 vehicles where SAE 5W-20 is specified should be serviced at the recommended oil change intervals using SAE 5W-20. This oil is an improved formulation to improve fuel economy.

Testing has validated this viscosity grade can be used in many previous model year vehicles. It is recommended ALL vehicles on the following Vehicle Application Listing be service with SAE 5W-20.

Does this make since to anyone? This looks like a misprint to me.. where SAE 5W-20 is specified should be serviced at the recommended oil change intervals using SAE 5W-20. ..:confused:

Slowtime

01-10-2003, 04:53 PM

Sounds like a legalese restatement to me. Just driving the point home in the most confusing way possible.

Unless it's a missprint. :shrug:

PizzaSlut

01-14-2003, 11:55 AM

I read a ton of articles on this and pretty much it seems that Ford needs to keep a certain mpg rating over its whole lineup of cars and this formulation makes their cars get the few tenths of a mile per gallon increase that they need to keep over the limit. So basically, if you want to get a couple tenths of a gallon more, switch to this stuff. I'm just going to keep on using good ole' 5w-30.

IndyCougar

01-15-2003, 01:17 AM

I run 93 or better octane fuel since i had my Superchip installed. I was told by the dealer that sold it to me that i needed to run 91 or better to get the performance boost and to avoid a knocking noise in the engine. I believe the guy was being truthfull to the best of his knowledge since it was my stepdad and all. Just wondering what you guys say on this one.

IndyCougar

blacklighting

01-15-2003, 03:27 AM

I run 92 octane since I have nitrous on my cougar. Since I switched from 87 to 92 octane I have also noticed better gas mileage. The oil I run is Red Line synthetic 5W30

topgunz1

01-15-2003, 05:38 AM

I usually run 87 even though my SVT says premium fuel only, I just cant afford it but from what I read, it doesnt really matter. I put in midgrade last fill, but I didnt fill up all the way cause the pump stopped early and I didnt know, so I have no clue if it helped. Oil currently in there is havoline 5w30, I think I'm gonna stop usin fram filters from what I've seen. those ez grip tops sure are convienent for our tight engine bay.

Cat88Extreme

01-17-2003, 12:30 PM

Some more info to ponder by Terry Haines, Dom, and others: Fuel Octane (http://www.fordcontour.org/FCOForums/index.php?act=ST&f=28&t=1342&s=4804d5e3aaa2de9c0f25ee8f4777fdac)

Just some food for thought.

Busted

01-17-2003, 02:22 PM

I hate to be redundent but I use 93 octane (because I see a substantial performance and MPG increase also) and Mobil full synthetic 5w-30. I have been using synthetic oil since my first car and have never heard or expierienced anthing bad about it. The mechanic who fed the line "if your motor is used to conventional oil the synthetic oil would be harmful" is full of it. If your thinking about switching over then the only thing you have to do is change your oil at 3,000 miles the first time to "clean out" all of the conventional stuff. I'm also trying K&N's oil filter for the first time and don't really have much to say about it. For the people using Fram filters and think that sure grip makes it easy to change then you would love the K&N. It has a 1" lug on the end of it. Nothing is easier (except for having someone else do it) than using a ratchet to take the filter off.

ps There is nothing wrong w/ owning a Harley.

caenus

01-17-2003, 07:02 PM

I actually hated that sure grip on the Fram cause my oil filter ratchet would just keep sliding. Love the K&N filter because of the lug. Even though they are a little pricey, they remove more micro particles from the oil and easy as hell to install/remove.

mp91

01-19-2003, 04:33 AM

Mobil 87 Octane Gas & Mobil 1 5w30 SuperSyn Oil

Zip

01-20-2003, 02:31 AM

Dominic's 87 Octane Gas w/ the Discount Card saving (3 cents normally, sometimes 6 and 9 cents off the gallon!!!!!111, but when I really want performance, I fill up at the truck stop, Diesel helps.) and I don't use oil, I use gerbil pee.

No... I run 92 (is that what IL has? I just press the most expensive one) and whatever the local Tuffy put in my car. I definately see a great increase in mileage... no doubts about that, and I drive the same route every day under the same conditions, by the same people, it's monotonous... And I run the same stop lights and signs every weekend night... ;)

I don't care what the premium is doing to my engine, it's getting me a significant amount more of mileage for an extra buck or two. I definately get great mpg, 18 in downtown driving, but the usual stop n go stop signs and residential is 21 MPG... Only performance is dual exhaust, K+N air filter, and the tornado air intake thing (and the IAT mod when it's warmer out.) (Which all help ALOT.)

My car's now out to be driven like a race car... It's my first car, it's got 30,000 miles on it (2000 ATX)... It's not some fast sports car (looks like it, it can beat alot of things but...) ....

Breaking it down to what alot of people are saying:

Premium clearly recieves better MPG... and unless your really looking for pure performance or keeping that engine perfect or whatever... the MPG increase is worth it. (Why the hell would you want to get cougars to perform when stock cars will still run them over.:))

just my .02 cents... tired... none of that made sense im sure