Fink

Lately, I have been noticing a rattling noise (sounds a lot like knocking) coming from the engine.

Well today, I went to the gas station and filled up with Plus (89 octane) versus my usual 87. If this solves my problem and makes me ride a little quieter will it hurt my truck to use the 89 from now on if it has been drivin all its life using 87?

Thanks guys!

I know this is probably a serious nOOb question..but I am just curious.

Thanks again

884runner

in my 88 3.0 i had to start useing plus. for a while i was using premium but that got to expensive and i could run fine on plus. If i still ran on regular then my car would always make a ticking noise and never get my up my driveway. i don't know how to explain this but that's just the way it worked out.

Fink

I am fine with running Plus in it, but will it hurt anything to just suddenly start using 89 versus the 87 that the truck is "used to"?

Thanks for the reply!

As long as its OK to use the 89 then I will start using it.

884runner

didn't hurt me one bit, and i switched a long time ago and haven't had any problem that is related to the fuel change that i can think of so i say go for it.

Fink

Cool man, thanks!!

HBoss

It won't hurt anything. As a matter of fact, depending on alititude and age of the motor, many engines require higher octane as they get older to ward off pinging and/or knocking. Because they don't burn as efficiently as they did when they were new, they may need higher octane just to keep running properly.

I use 89 in mine because I get some knocking when I floor it and the RPMs are between 2k and 3k. If I use 87 it knocks when I accelerate hard at those RPMs.

gwhayduke

It appears that I get better gas mileage on the 91 octane I get from Sam's Club. I guess I need to do some serious testing, but premium is about a .10¢ more and it seems to get me about 1 more mile per gallon. So expense-wise, it's probably a wash.

rimpainter.com

Yep, what everyone has said is right. On older engines (due to carbon build-up, etc) higher octane may be required. However, you should only use the octane that prevents ping/knock without going overboard.

In other words, if 89 works, dont use 91/92.

For me, I have to use 91 because of my ISR mod. If I dont, it pings and the knock sensor retards my timing, making it slower.

There are lots of threads regarding ping/knock if you want more info.

rimpainter.com

By the way, if anyone cares Costco filters the crap out of their gas (which is good because I buy my premium there). My dad works for them, and spoke to their purchaser regarding their gas. He told him that the filtering is extensive and they make very little (if any) off people buying gas from them. Costco's profit is made primarily on memberships.

Memphis4X4

Christian: Tell your dad that COSTCO gas rocks!!! I have used their gas for last 3 years in both of my cars and found it is good stuff. I'm glad to hear that they filter it extremely well. In addition to being good gas, there's an added bonus of the price difference between the COSTCO gas versus other places saves me enough money to more than cover the cost of Membership!

David

HBoss

Damn..we don't have any Costco gas stations here.

Hey 96, do you know anything regarding the quality of other gas stations? Namely, Shell, Esso and Petro-Canada?

rimpainter.com

Sorry Hboss, I really don't. I do know that all stations in the US are Audited regularly for flowrate (min/max) at the pump, and to make sure the gas you are getting is accurate to the cost, but that would not tell you much about filtering.

I know Shell failed many of those tests, but that may be due to independent station operation, not Shell itself.

rimpainter.com

Hey, he was just as excited to hear that as I was!

Besides, he works in the Travel (cruise) department.

I agree about the cost savings and membership. Oh wait, my membership is free!

Memphis4X4

That's awesome......there's nothing better than getting something good for Free!!! Besides selling good gas, COSTCO has a great Meat and Seafood department!! That's where I buy all of my steaks!!

Well, I guess I'd better turn the post back over to the question at hand, which is about Octane. I didn't want to turn it into a commercial for COSTCO.

By the way, 4x4Fink, the computer will adjust overtime for the difference in octane. You should be ok to switch back and forth with the engine that you have.

David

Jason B

I run 87, what the manual says.

I was just in a gas discussion on another board and thought you guys might find this interesting. Some of this is quoted, but I agree with it.

Hard, empirical research has borne out time and again that a well-tuned late-model engine (OBDII) runs best on fuel within specifications made by the manufacturer. Running higher octane fuel is almost always a waste of money, no matter what the seat of your pants or your brother-in-law the mechanic says. Engines without knock sensors, older engines with carbon deposits, and engines with the effective compression ratio modified (i.e., supercharged) will need the premium stuff. Run the lowest octane the manufacturer recommends. If it doesn't knock under load, stay with it. I love it when a truck owner says that he "treats" his new vehicle to a tank of premium. The only treat in that situation is going to the oil company.

This link is below is pretty interesting. One of the things they did was put 87 octane in a new BMW M3 and compared the results. Read this link in depth.

There are three pages total:
http://www.caranddriver.com/xp/Caran...e_gasoline.xml

SteveS

JB thanks for the link. 90% I knew, but always link to see it in print from time to time, and 10% was pure learning. I really liked the way they worded it about "Cheapskates burning regular in cars designed to run on premium fuel..."

I'm not a big fan of Costco and their total disregard for property owners rights, but this is not the forum to air that. I just haven't had my soapbox out in a long time.

So has anyone found their rig needs 92 octane after 200K (or at some real high milage point later)?

gwhayduke

Great article!
It quantifies what Consumer Reports and Click & Clack have been saying for years. It also offered a possible explanation for why my old girl seems to get a little better mileage on the expensive stuff.

jharris2

I get 10% worse mileage on Sam's gas -- go figure.