Honestly has anyone noticed a difference while driving on regular and premium?
 

The manual says a slight decrease in "Performance" but have u guys really noticed anything like horse power difference etc.

I do.

Feels a bit more sluggish when using Regular. 89 feels fine. 93 is the most "stable"

I just stick with 93. Gas is a rip off anyway, might as well use some good ones.

Think of it this way...
If you pay an extra $0.20/gal for the premium and you fill up a 13 gallon tank, how much more are you paying for the premium gas?
0.20*13=2.6
So you're paying an extra $2.60 total for the premium!
Is it worth arguing over?

I lost 10 hp on the Cobb dyno just dropping to 91 octane for the STU car WRT the dyno posted on this site

89 octane is fine with the stock ignition timing

I've talked to a mazda mechanic and he said that premium contains lead which in the long term clogs and damages the engine, once again u may not feel a difference in the short run but in the long term the lead will damage the engine.

fixed

56,000 + miles of 91 octane. Never seen a drop of 89, wouldn't know...

*removed due to improper word choice*
*intentions are better clarified then this post further down.*

kevin.

nope, the ignition timing maps are *designed* for premium octane, california emissions vehicles are tuned for 91 octane. While the PCM will adjust the map based on knock sensor data and other inputs you want to keep everything as close to what the PCM expects/wants as possible.

true, 89 octane *probably* wont hurt, but thats because the motor isn't designed to have the octane as it's only lifeline. a change in octane on a highly modified, built to the borderline of safety and tuned on 93 octane can blow from one run on 89.

lead in street gas is illegal and would destroy your cat, the tech you spoke with is wrong. Otherwise lead is actually a lubricant and wouldnt clog or do any other damage to the motor's internals. The only time you'll find lead in fuel is higher octane, non-street gas. Such as in cam2's 105 octane leaded fuel.

If you have a midpipe you can run leaded gas with few if any problems, but premium fuel contains *no* lead, or it wouldnt be legal for sale in the US for use in a street vehicle)

cause your car wasn't tuned to the 91, it was tuned to the 93, therefore your timing was off.

tune it to 91 and you'll achieve the same results if not *better* due to the faster burning and advanced timing required.

personal opinion, you own a $30k+ *sports* car if you cant afford the gas it requires sell it since that is going to be the least of your worries down the road. If you *have* to use standard octane look into an auxiliary injection system to add a layer of safety against pre-ignition/detonation.

kevin.

Street gas nope. no lead

Race gas, some yes.

Lead is a wonderful lubricant, try to get a piece of paper, and rub your pencil on it. Then feel the paper, nice and smooth ,right ? (yeah I know some pencils are made from graphite, but lead is still wonderful)
its just that Lead is not that wonderful for human beings.

i've had knock on 87 but none on 89 and of course never on 90-whatever

kevin thanks for getting that lead bit so i dont have to buuuuuuttt...

you are wrong about lower octane fuels having a higher burn rate than higher octane fuels. the octane tells you zip about the burn rate. you can look up previous discussions for the info i and others have posted before or i can post it here later when i have time.

geez i swear someone else jumps on me for simply using common phrases....this is getting ridiculous. "Burn rate" may be incorrect but it is a phrase used as a simplification for the definition.

so by "burn rate" I was merely "dumbing down" the scientific process and in turn simply describing it's results rather then it's definition. "Burn rate", in my wording, is used to describe the resistance to pre-ignition (preignition is the early explosion of the fuel caused by internal engine temperatures exceeding expected/calculated temps). The resistance to pre-ignition = octane. it's that simple when broken down. Yes other things help resist pre-ignition, but octane was being discussed specifically in my post not FUEL as a whole.

I will attempt to no longer use simplified terminology here, or when i do use simplified terminology I will amend it with a "*" and provide a full footnote as to it's specific meaning. I was unaware of the scientific level of speech used here apparently, my bad (do i define this now?)

seriously i'm tired of my *words* being jumped on, at least have a level to stand on, i'm sorry some of us do too much in one day to be able to sit squarely at the computer and completely think out every single thing we type. As we speak I'm building a motor actually, so again my bad* if my wording suffers, what are you doing while on the forum?

hell lets throw in another quote thats almost identical to my original post:
wow, almost identical to what is written in my first post. Who did i get this clip from? The wonderful folks at Cam2/Sunoco. Wanna argue with them about fuel? I mean you do know who they are and their position in the "fuel" world afterall, honestly i'd rather listen to them then "another post" on here. Unless there's a cam2 scientist or engineer in said post...

now if we want to be super technical in reality unless you know your fuel's specific antiknock index, represented in the formula (R+M/2) (R=RON,M=MON). But this is a casual forum...i thought.

kevin.

*my bad - slang used to admit, in 1st person, the failure to accomplish, complete, or do something.
Ex. "i forgot to do the laundry, my bad"

apologies for aggressiveness but seriously this week alone i have had 5 posts taken apart due to simple phrases being misinterpreted. If you need a definition or better explanation of one of my posts or even a specific word my PM box is WIDE OPEN and monitored constantly by my iphone, no need to waste a post (i believe this is even part of the forum rules?), i mean i expect this from typical forum members but.... I do understand that you assumed i was using the industry standard terminological definition of "burn rate" however I was simply using it as basically my own personal abbreviation, in a sense, you should've just PMed me and it would've been easier.

Premium usually has more cleaning additives - correct? If so, it seems like that makes it worthwhile right there, particularly on our motors.

Also, one issue I became "sensitized" to a few years ago is that no all gasoline is created equal, from a cleanliness standpoint. In fact, my home state, Oregon, is purposely shipped some of the dirtiest gas in the nation. Why? Because we have some of the cleanest air in the nation, so we can "afford" the crappy gas & it's associated increased emmisions.

For that reason alone, I tend to buy premium, with the (perhaps) hope that it is cleaner than regular. Again, if for no other reason, the additives would hopefully help combat the dirty gas.

Don't know if the additives present in premium actually do anything, or if it's marketing crap. Anybody know?

debatable. Every fuel manufacturer adds its own "special mix"* nevermind government rules and regulations requiring certain amounts of specific "ingredients".

i'd say each probably has a specific benefit but its hard to choose which is better in overall terms.

kevin.

*special mix - used in place of "proprietary scientific/chemical combination of additional chemicals or additives to the fuel based on results determined in their own personal labs"

sorry you took that so badly. it was supposed to be more of a light hearted jab thats why the long buuuuutttttt. judging from your other posts i was surprised to see you make that error. its a pet peeve of mine to not let the octane misinformation go because i have spent so much time previously trying to correct people spreading around the incorrect info.

side note- when i posted that i was

unpacking groceries
feeding a 10 month old
starting dinner
helping my 4 year old pick up his stuff
taking out the recyclables

so yeah some of have more to do than sit at the computer :D:

sorry i missed the jab, i've received some rather insulting messages lately and have been on edge, my apologies, im taking medication (aka good old jack d) for my edginess once this motor is locked up.

I just dont understand why unnamed people have decided to attack me, so ive been on the defensive lately. nothing like having other people ruin the party huh?

BTW, you win, just *having* a kid eliminates any ability of full focus on anything....ever. lol.

kevin. (not an angry or rude person, don't run away anybody, ask those who've met me I'm relatively reserved and a heavy thinker.)

Today is recycling day for me too :)

More about Lead. Lead was used to increase the octane of gasoline. A byproduct was that it protected/lubricated the valve seats. Lead also leaves deposits. This was bad enough with the spark plugs in the old days. It would turn into Lead fouling between the electrode and ground. Plugs would, at the most last 20k miles. Today, on the piston engines, they last 100K. It would be even worse on the spinning rotors, seals and rotor housings on our engines.

As far as the raw stock goes, gas is gas. It comes from the cracker in every refinery in the same state. It is later that additives are used to raise the octane, reduce pollution and add detergents that are used to keep your fuel system clean (eg. injectors). All octane levels of gasoline have detergents. The type of additives to reduce pollution is determined by the Federal and State governments.

57k on 87 octane Shell. I don't drive the hell out of my car either, so I don't hear marbles in the can. When I first got it, I tried 87 octane after reading the manual and could not tell the difference between regular and premium. I also read early on that may RX7 owners had used 87 octane successfully. I'll post when I need a new engine :).

Welcome to the Club mate....You want to be an Australian, :lol: , I get my words "taken apart" ALL the time...I know what I mean and that is all that matters...and I know what you mean...and that is all that matters?:banghead:

Seriously, don't let it get you down and PLEASE DO NOT Let it stop you from forwarding your knowledge and Experience here...OK Kevin.

You will always get accused of talking too much or not enough information, or can you "back up what you say" comments...

While NONE of us are Always correct (some think they are), I like to think in most cases you, I, and a few others (regulars) post what is true as they see it.

Take it easy mate...

Ash

OH, BTW, I remember back in the 70's before "Unleaded Fuels" Mazda rotaries HAD to run on "Standard" gas, low Octane and low lead, it was a NO NO to put in High lead or "Super" fuels. You were told that "No" performance gains in using Super gas, the Cheaper Low Lead fuels were a marketing advantage for the rotary back then.

did not know the long term effects of lead, thanks for the correction. My car's motors only see 15k before refresh so it never effected me personally. knowledge of the situation highly appreciated, thanks :)

kevin.

Wow, this is more information than I thought I'd find randomly searching a forum. Thank you.

I have one question though. Isn't it possible for companies to just say that they are giving you high octane gas yet are truly giving you crap without letting you know? How can you separate the lies from the true without the proper knowledge of the intricacies of each company and whatnot?

Forum/Car Noob,
Ace