Do you use premium gas?

[Groves]

I'm buying a 2009 Odyssey from my in-laws. They're good folks.

I've never ever bothered putting anything but cheap gas in my vehicles.

I'm just checking in to see if that's foolish or as I have thought, not a problem.

Yes, the valve guides would have suffered from unleaded in my '62 Buick, so the lead I did ad back in.

These modern cars, not so sure. What say ye?

[Radar Chief]

Originally Posted by loochy

I think most modern cars have knock detectors that dial things back if excessive knock is detected.

Yes, to an extent but that adjustment has to be within the parameters of what the engine can adjust for.
For most fuels available in the US I don't think it's a problem just stay far away from that E15 crap they're starting to push.

[Perineum Ripper]

91 or 93 in my motorcycle and 87 sometimes 89 in all the cars except my Passat it takes diesel

[SAUTO]

Originally Posted by GloryDayz

Yeah, my 2002 Silverado has one that's pissing me off! Right after I cleaned the engine (t'was dirty as a power steering line had been leaking for a few months!!!), but ever since I get the knock sensor warning. I've read that it might be from the moisture I introduced while cleaning the engine, but it's been more than a month and I'm getting tired of resetting it.

And the fix seems like it has the potential to break as many things as replacing the sensor would alleviate.

But hey, it's a 2002, 250,000+ miles and I could not be more happy.

Yep you ****ed those sensors, probably should get a harness also. They are cheap. You could do that job yourself easily. Add in the problem solver intake gaskets and that thing will last forever.

[Holladay]

Just read my manual. On the CTS-V recommends 91 for better performance but can use 87. This darn thing has so much power, don't need anymore performance. My body can only take so many G's.

I am looking at trying to get better gas mileage thou. It would help if I could keep my foot off the pedal That said, averaging ~20 mpg, goosing it a bit when I want my cheeks to flatten. Would the 91 give better mpg? From what I have read, it would avg out...more money in the tank but longer on the road?

What about getting a "mpg" tune/chip? No more power, but max mpg?

[Aspengc8]

Originally Posted by Holladay

Just read my manual. On the CTS-V recommends 91 for better performance but can use 87. This darn thing has so much power, don't need anymore performance. My body can only take so many G's.

I am looking at trying to get better gas mileage thou. It would help if I could keep my foot off the pedal That said, averaging ~20 mpg, goosing it a bit when I want my cheeks to flatten. Would the 91 give better mpg? From what I have read, it would avg out...more money in the tank but longer on the road?

What about getting a "mpg" tune/chip? No more power, but max mpg?

Most stock tunes run a bit on the rich side for safety. You can get a chip that leans it out, giving you more power and better MPG. Just switching from 87 to 91/93 is not going to bump the power output up.

[Holladay]

Cool. Thanks.

I did read in the manual that using the 91 would provide more performance, not sure how much.

So a new chip will make it more lean which provides more power AND mpg? I thought that there was a trade off between power and mpg. Up one and the other decreases etc.

[Warpaint69]

Originally Posted by Radar Chief

Never heard of that one.
But I do know that running 91 octane in an 87 octane motor is sending more unburned fuel down the exhaust and can clog your cat(s). Saw that one for myself.

Running a lead racing fuel will ruin cats too.

[Warpaint69]

Originally Posted by Detoxing

But as the article noted, the car may start experiencing "knock" and if it does then you'd want to switch back to the appropriate fuel.

When i bought my Turbo Mazda i asked my business partner (A master fabricator/technician) if he thought the 91 Octane was required. His advice was to try it. If the car starts pinging louder than normal, then you need to switch back. Mine did, so i switched back.

My car is also known to have timing chain issues, which results in catastrophic engine failure. I have to wonder if those timing chain failures that people are reporting have anything to do with using improper fuel.

Knock and pinging is also known as pre ignition. Thats when the fuel is being ignited before the actual engine ignition process. The greater the octane fuel rating the greater its resistance to pre ignition.