Wrong Gas - Problem?
 

Hey Guys,

Dummy me was half asleep this morning and put about 2 gallons of 87 octane in the car before i realized what i was doing. Filled it up with 93 for the rest. Do you think this would cause any problems??

Not 2 gallons.

wont cause problems as long as the gas mixes. so you should get some buddies to help your rock the car around and make sure it mixes.

you dont think that would happen just from driving? I take back roads to work that are windy...

hey, at least you didnt put that e85 crap. my buddy did taht one time on his accord and it knocked pretty bad. lol :D

you're fine!

Thanks guys for your info. I didnt think it would do anything but figured I would ask...

I did the same thing but I think I filled it like 3/4 of a tank! I drove it slow until I got half a tank, then filled it with 93 octane, and all was fine...

While not recommended, you could burn a full tank and not harm your engine. You will give up peak performance, but you won't hurt your engine.

After Hurricane Katrina, the only gas I could get in the New Orleans area was regular (and thankful to have it after a usual 30 minute wait in line) for almost two months, and I didn't see any noticeable decline in the performance of my Acura CL Type S.

I'm not turning this thread into one of those moronic "why can't I use regular gas" troll fests, just trying to assure the OP that he's got nothing to worry about.

You should be fine, don't stress. Burn the gas till last drop then refill.

i hope you realized at some point i wasn't serious....

Oh my... it won't be long until the opposing heptanes and trimethylpentanes fuse in an exothermic transmutation that engulfs the car and detonates any surrounding dihydrogen monoxide molecules in a chair reaction on the order of the Hiroshima bomb...

In most cases I've seen, it generally takes around EXACTLY TWENTY-FOUR HOURS.

:bowrofl: :roflpuke2: :bowrofl: :roflpuke2: :bowrofl:

Please, have some coffee before you get in a car and drive. Driving that tired is almost as bad as driving drunk. Out of love for this forum and its members, I don't want to see another Z brother get hurt, lose there car or both? :)

2 gallons is no big deal. If you use gas stations that don't have a separate line at the pump for 93 your getting about a gallon of 87 (what most people pump in their car(or whatever was used by the person in front of you)) and your car runs fine.

No, because your overall octane will still be above 91, which is perfectly fine.

Like the others have stated. Your fine just burn the entire tank and restrain yourself from really getting on the engine. It'll be fine.

LOL!

Exactly. Octane rating is merely the ratio of octane to heptane in gasoline. Given the volume of the Z's tank, and assuming you filled up, prolly puts you right around 91-92.

Duh, 2 gallons mixed with the rest 93 octane is probably like=92 octane...dont worry be happy.

I thought that gas with AKI 87 or RON 95 is possible with VQ37. :shakes head:

RON 95 = (approximately) AKI 91

Yes, you are right. Just finded, that AKI in USA is different to other ones used in different countries. AKI used in USA is 4-5 points lower. In other countries using AKI it is between 8 to 10.

Based by twice read this article Octane rating - Wikipedia, the free encyclopedia

Strange, that is recommended RON 98 in Europe - see no difference to 95.

98 RON is roughtly 94 AKI.

You can get a pretty accurate estimte by taking the RON value and multiplying it by .95 to get the approximate corresponding AKI (i.e., 98*.95 = 93.1; 98 RON = ~93AKI).

Most ECU's have an ignition map that starts higher (for example, after a reset) than you see over the course of driving and pulls timing based on knock detector activity and also transient conditions like air, water, and oil temps. It will add timing back in as conditions change, of course.

So, threotrically, higher is better, at least to a point. You would probably see diminishing returns past 95 AKI /100 RON without a re-tune.

Also as you start creeping into higher and high octanes (well over 100), it gets harder to ignite (especially when cold) meaning potentially fouled plugs, higher emissions, etc. but no more power without a re-tune of the spark maps (unless it was under so much load and such harsh ambient coniditions that it was seeing some knock, of course...)

So basically anything betwen 91 AKI (95 RON) and 95 AKI (100 RON) is good, with 93 or 94 AKI probably being about optimal on the factory tune in normal, but spirited, driving condtions.

If you were never going to put much load on the engine (i.e., drive slow, wihout any sudden acceleration or high speeds), a lower octane would work in a pinch to keep from getting stranded or something, but it's far from ideal or recommended.

The manual states you can use a lesser grade gas if needed.

^^^ Right -- to avoid being stranded. But beating on the car with < 91 AKI fuel is ill advised.

The manual also says to not do more than half a tank, and to refill with the proper octane ASAP, if memory serves...

Really useful info Jordo!

My TT TFSI 2.0 (new model) done 80000 kms without any issues on RON 95. That engine is RON98 only (in BWA version). But actually I didn't see any difference in long term use. Maybe it is caused, that gas stations are selling RON 95 as RON 98 (I could be wrong, but in Czech is different Shell V-Powe Racing than in Germany, which is our neighbor).

By long term I mean around few thousand kms and really spirited driving sometimes - 240 km/h for one hour on autobahn.

What is really strange to me, is fact if is recommended AKI 91 in US, why is only RON 98 in Europe? Maybe I'm wrong because search function doesn't work to me for now.

In the US, due to ultra strict emissions laws in California, pretty much all vehicles sold in the US that require high octane fuels are tuned to operate normally with 91 AKI.

That said, many gas stations in the rest of the US don't carry 91, but have 92, 93, and even 94 AKI.

You can even get 100 AKI at the pump in some Sunoco stations -- although it costs nearly twice as much as 93 AKI, and isn't particularly useful unless the spark map has been tuned for it... or maybe if you wanted to be extra cautious running laps at the track on a hot day in the summer.

Don't know if you are getting 95 or 98 RON or whether the label is accurate -- there's also MON, which is slightly different... so maybe 95 RON = 98 MON? Not as sure on that one...

Anyway, either 95 or 98 RON is fine, and neither should result in much (if any) of a significant difference in performance unless you are pushing it really hard in harsh conditions, in which case the higher of the two would be preferred but probably not essential.

I thought ethanol boosts octane, so you get less knock not more.

I think the reason he refers to it as crap isn't due to the octane rating. All things the same E85 will run leaner than regular gas. I saw a video where they were talking about the differences and the E85 needed roughly 30% more fuel to be happy.

I think E85 has a totally different stoichometry than gasoline (needing more fuel per lb of air would support that assumption) and also requires alcohol safe components to avoid corrosion.

Basiclaly, you can't run E85 in a vehicle that isn't tuned/designed for it.

Good, cuz I thought you were crazy for saying that lol.

I just dumped a whole tank of regular (85 I think) into my beloved Z. Because I'm awesome.

I should basically assume it's going to run a little off for a bit but I'm not looking at any serious issues, right? I don't track it or anything.

If I was you, I would go to a paint store and toss in a few gallons of Toluene. It will raise up your effective octane in the tank. Do not buy any 'octane booster' nonesense from a auto store: its weaker and smaller in quantities then the good stuff from a paint store.

Xylene can also used but I have found Toluene easier around me. I would not add more then 2 gallons (keeps it < 20% toluene mix)

Ex:

Toluene (R+M/2) Octane: 114
Xylene (R+M/2) Octane: 117

Average Octane = (Base x Qty1 + Change x Qty2) / (Qty1 + Qty 2)

Example for 16 and 2:

((85 x 16) + (114 x 2)) / (16 + 2)

Which is 88.2, pretty close to 89.

Now, if you are at sea level (DFW) and not altitude, 85 octane is cat piss and I would be a bit concerned about running that in any car tuned for 91. Sure the knock sensor should detect any noise and reduce your timing maps but that is a pretty large drop.

If it was 87 (I hope), its a bit better story and the toluene will get you above 89 and you can rest easier until you get 1/2 a tank left, then go find a sunoco and fill 1/2 with 93 octane.

Finally, please smack yourself for putting in a full tank of 87 octane. This is your Z doing it, not us: nothing personal, and its for your own good. :D

- b

Thanks for the advice.

It's important to note this occurred an hour or two after my wife (not a car person), completely unprovoked by me, comments on how much she likes riding in my car and what a great job I've done taking care of it. I'm a bonehead.