red wrx

I know, I was distracted.... I just put 1.5 gallons of 87 CHEVRON on my STI in SO CAL where 91 is the highest gas. I stop the pump and then completed with 12 gallons 91. The car was pretty empty when I put the 87 and after the 91 it is in the full mark but not completly full.

What should I do??? Leave it like that or buy an octane booster. The car only has 650 miles on it.

How much does subaru can resist on knoking, pinging or detonating, or are the internals damaged right away? I read on the owners manual that some knocking is ok on our cars, but what about engine damage? Does that means that some knocking is ok....

Also in my case or when you put the wrong gas, what can happen knocking, pinging or detonation because seems to be similar terms.

After you fill out the tank how many miles does it take to the car to suck the new gas, because when I heard the knocking/pinging sound it was after 1 1/2 miles of driving with the mixed gas (too soon????). I drove around 70 miles after that and I did not hear any noises, I only heard the noises 1 1/2 miles after I put the gas it was maybe my imagination??? During those 70 miles the car was perfectly fine. Is it possible that the ECU learned while the initial knocking/pinging??

I am concerned about any damage in the long run.

I know I have been kinda repetitive, but when you have a new car and a picky owner that what happens.

Thanks for your replies....

Superglue WRX

You can use 87 octain in emergency situations (that's also in the manual). And since you're still breaking in the car, there's now even more reason to go easy on the gas.

Step 1: get octane booster

Step 2: go easy on the gas and do your best not to make any boost

Step 3: drive as much as possible until it's time to fill up

Step 4: fill up with 91 octane and consider it a lesson learned

Onizuka

iTrader: (17)

I would reset your ECU. Buy one of those plastic emergency gas tanks, fill it up with 91. In fact, you may want to buy two of them. Go home slow, easy on the gas, drain it (put it in another car if you got one), and then use the two emergency cannisters. Go back to the gas station and get 91.

Wingless Wonder

iTrader: (7)

The WRX's ECU will sense engine knock but if you were able to complete the fillup with 12 gallons of the better stuff vs 1.5 gallons of the crappy stuff, I think you will be fine if you take it easy with your driving. Prolonged use of an entire tankful of 87 octane is not good because the ECU will make changes to the ignition, boost, and fuel mapping to be pig rich to avoid detonation. Fuel economy will go out the window.

You can also follow the suggestions of your fellow members if you find that having that crap gas bothers you. I've never actually put less than 91 octane in my gas tank so I can't say for sure if you'll notice the effects right away.

--
0==WW==0
"…axles of evil…" - george w. bush

RedStage

iTrader: (4)

Stay out of the boost for sure.
Like said above if you take it easy and run the tank down to as close to empty as possible for the next two or three tank fulls, and fill up each time with 91, you should get rid of the 87 in the tank.

At least you caught it before the tank was full of 87.

VRT MBasile

iTrader: (17)

you'll be fine, just take it easy. I filled up with the 87 BY ACCIDENT before and my car is still fine, I did add octane booster and took it easy. If you want peace of mind, find someplace that hass 100 octane at pumps and once youre down to 2/3rds of a tank top off with some 100...your car might even be happy after that one

(and in my defence, the station I used wasnt my normal ones and the pumps were in the opposite order from my usual statio )

highwayman

Are you guys serious? 1.5 gallons of 87 octane mixed w/12 gallons of 91 octane is not going to do or affect your STI. The little amount in there will have not damage or cause it to ping on a stock motor. We're talking about a minor bit of 87 mixed w/alot of 91. You guys sound like he dumped 1.5 gallons of diesel in there. Don't worry, drive accordingly to break in & keep 91 in it.

awns729

iTrader: (1)

IIRC the ECU will just go easy with teh timing if it senses knock. Subaru's have excellent ECUs. You only put in a little bit of 87 anyway, so I strongly doubt any long term harm was done. The ECU might not have even modified timing, and if it did, it will readjust it (which'll get you the same power/mileage as before) after a few tanks (at most) of 91 octane. Don't worry.

SpicySpaghetti6

you're overreacting a bit lol. dilute your 87 with 91 or higher. if you're really worried drive several blocks going 15mph and drain your gas, then refill with 91.

your car is not going to die.

Wingless Wonder

iTrader: (7)

He posted this more than two weeks ago. I'm sure the problem has worked itself out, one way or another.

--
0==WW==0
"…axles of evil…" - george w. bush

colorado_sport

hey just use the gas then when it starts going down refill with 91 octane it will be fine its call blending after about or week or two off puting gas it will be ok.