What oil and octane fuel do you use?

[Exodus_2pt0]

Wrong. Normally wouldn't point this out, but you seem kind of nit picky on things and very detailed.

Care to elaborate?

Because... Well... He is right.

And even new cars do not advance timing beyond what they are tuned for. All they can do is PULL timing in the event a knock sensor reads detonation.


Class time.

High octane resists burning more than 87 octane. This means that you can advance the ignition timing earlier in the compression stroke so that the little fire in your cylinder will be at maximum pressure at the right time, to slam that piston back down. If you run a lower octane fuel with the further advanced timing for a 93 vehicle, then the combustion happens much more rapidly, and your piston gets pushed down before the crankshaft has rolled past TDC (Top dead center).

What are the credentials of all these people claiming knowledge on octane ratings while stating that premium makes any difference on a stock vehicle? If your car is not tuned for premium it will not make a difference.

Open up a engine with 100,000 on it, both were run quality fuel and synthetic motor oil with proper maintenance and the only difference being; One was run with 87, the other with 93, you won't notice a damn difference. In my 10 years as a professional Auto Tech I never once removed a cylinder head and said.

"Damn this guy must run regular octane"

I am not attacking anyone here, just trying to clear through the misinformation so that we don't have people wasting their money on fuel that they don't need. Gas prices are high, we can't help that. Knowledge will save cash though every day of the week.

[Emre]

pics

Here's the 14-page build thread:

http://www.r3vlimited.com/board/showthread.php?t=162904

It's coming along nicely.

[priapism]

"Shit" fuel is fuel without detergents, and that doesn't have anything to do with octane. Running a fuel injector cleaner once in a bit is helpful if your car runs funny.

I've been running 89 because, well, that's what I thought it needed.

[jeffnhiscars]

My 2c...and this from someone who has used 91 forever since most of my cars have required it (see sig).

My understanding of octane rating is that it has nothing to do with the energy content of fuel or "how long it takes to burn". It is strictly tied to the temperature of detonation after which they all behave the same. Higher compression engines need higher octane so the fuel ignites AT SPARK, not at some random point in the compression cycle. If you change your timing, that could theoretically impact the fuel you can safely use as the air temp in your cylinder at detonation will also be changed..ie at 10btdc the air is not as dense or hot as at 5btdc. Diesels have higher compression ratios for just that reason since <drum roll> they have no spark.

Bottom line on fuel, if you do not get pre-ignition ie pinging, then you are wasting your money on 91 (ask me how I know).

As for oil, the main reason to change it is because it gets diluted from unburned fuel and condensation, not because it breaks down (hence the recommendation to change more frequently for stop & go driving). If you are tracking your car then synthetic definitely makes sense since it doesnt break down easily..and Im sure you change it every race. For a DD synth will get contaminated just as quickly as dyno. As much as we love these cars they are NOT all that efficient and even if by design they were, show me one that doesnt have some form of intake leak that throws out idle, mixture or hasnt had its timing messed with. My 2004 911 was VERY efficient and they said to change the Mobile 1 every 15k. It was as clean coming out as going in and clearing it didnt break down..but that was a Porsche.

The manual says 20-50, my car sounds like crap with anything thinner (ok its an M10, it always sounds like crap) and it thanks me every 3k when I change the dyno w a good filter.

Just sayin :-)

[Mr. Tasty]

87 in an '87 eta. Whatayaknow

[Killacortes]

20w50 91+ octane because race car! Jk just dinan chip :)

[Raxe]

for someone chastising me for believing BMW recommendations you sure are eating up big oil's "premium" label :|

Why do you think that 87 is "shit" compared to 91?
Octane doesn't indicate quality of the fuel. Mix 87 with alcohol and you'll raise the octane rating...but you aren't making a higher quality fuel by doing that. All octane does is tell you how slow the fuel burns. If your electronics can't take advantage of it, why do you think your car is running better?

I'm surprised this hasn't been mentioned yet, but quite simply: ethanol. 87 and 89 octane have a 10% ethanol blend whereas 91 octane is not blended with ethanol. It's fine for modern engines, but our older cars don't like ethanol and that's why you'd see a difference running premium fuel. Gasoline was different when the E30 was built.

[M3TROY]

"Shit" fuel is fuel without detergents, and that doesn't have anything to do with octane.

:up:

I'm surprised this hasn't been mentioned yet, but quite simply: ethanol. 87 and 89 octane have a 10% ethanol blend whereas 91 octane is not blended with ethanol. It's fine for modern engines, but our older cars don't like ethanol and that's why you'd see a difference running premium fuel. Gasoline was different when the E30 was built.

:up: exactly!

[smooth]

not quite sure why you are giving a thumbs up to primpism's post when you've been arguing with me for a few pages now for saying the same thing...right here in post #52 to be exact:

Why do you think that 87 is "shit" compared to 91?
Octane doesn't indicate quality of the fuel. Mix 87 with alcohol and you'll raise the octane rating...but you aren't making a higher quality fuel by doing that.

did you say anything about detergents? no...but I did way back in post #21

If you're running a stock system and using higher than 87 octane fuel you're wasting money and possibly causing issues. If someone is feeling a performance boost after switching it's likely imagination or possibly detergents in the fuel cleaned some things up...but the octane rating doesn't have anything to do with an engine's performance

And I won't speak for what happens up in Canada but in the US (at least in Oregon and California) 91 is 10% ethanol just like the rest

apparently you just like to argue regardless of the content of my posts. funny thing is I was just trying to help you out but for some reason you acted like a prick so now I've said my piece think it's time I unsubscribed

[Jaxx_]

I'm surprised this hasn't been mentioned yet, but quite simply: ethanol. 87 and 89 octane have a 10% ethanol blend whereas 91 octane is not blended with ethanol. It's fine for modern engines, but our older cars don't like ethanol and that's why you'd see a difference running premium fuel. Gasoline was different when the E30 was built.

can you clarify what would be damaged? Are you saying the engine would be damaged from running 10% ethanol blend? LOL

[Raxe]

can you clarify what would be damaged? Are you saying the engine would be damaged from running 10% ethanol blend? LOL

Where did I say anything about damage? The M20 wasn't designed to run on an ethanol blend, just because oil companies are saying it shouldn't harm anything doesn't mean it'll run as efficiently as the pure gasoline it was designed on.

[smooth]

come on man, ethanol as fuel in engines has been around since the 1800's...

now it's mandatory but it's not "new" by any stretch of the imagination, 10% blends were well in use in the 70's

maybe you're confusing it with E85 but I'm trying not to notice when a new post hits cuz this is ludicrous :D

[schtozo]

20-50 castrol gtx and 93 octane shell

[M3TROY]

not quite sure why you are giving a thumbs up to primpism's post when you've been arguing with me for a few pages now for saying the same thing...right here in post #52 to be exact:

did you say anything about detergents? no...but I did way back in post #21


And I won't speak for what happens up in Canada but in the US (at least in Oregon and California) 91 is 10% ethanol just like the rest

apparently you just like to argue regardless of the content of my posts. funny thing is I was just trying to help you out but for some reason you acted like a prick so now I've said my piece think it's time I unsubscribed

im agreeing with you wow dude your just lost... i dont know what else to tell you ;)
you seem to keep making and taking this personal, just stop already your coming off like a 15 year old school girl..

P.S. love your vert...cheers M8

[Dj Buttchug]

Here's the 14-page build thread:

http://www.r3vlimited.com/board/showthread.php?t=162904

It's coming along nicely.

awesome build.

for those arguing about fuel octane, i think the best way to put it is like so.

octane rating is the fuels ability to resist burn...