Fuel Question

[oldmansmonte]

So, there are many threads and a million opinions this, but I have some basic questions about gasoline.

I have three cars.

2011 Colorado 3.7(I5)
1995 Caprice Wagon LT1
1985 Monte Carlo SBC 350


The Colorado will ping like a sonofabitch if I run 87 octane, even though the manual says its fine. I have to run 93 in that truck all the time. The dealer said they "couldn't replicate the sound" when they did it(In other words in the 5 minutes they looked at it they couldn't find any billable hours for their tech). I've tried several fuel system cleaning treatments with minimal results. I'm at 70,000 miles and really don't feeling like tearing down the engine at this point to media blast the head so 93 it is.

The Monte has the GM performance engine and the manual says it must be 91 or higher so I just run 93 all the time. Why not right?

The Caprice responds basically the same to all fuels. I had been putting in 93 because the guy who tuned my Monte Carlo ECM(the guy in my tag from Kennedy's Dyno, a very experienced builder) says fuel loses it's octane over time, and the wagon is just a weekend cruiser so a full tank could last a month or 6 weeks. While I know the Octane losses are probably nominal I don't daily the car, so since it will cost only a few bucks more a month, I figure what the heck. But the more I read, it seems not only am I wasting money, but the car just isn't setup for 93 so I'm not getting the most out of the fuel. So I read the manual and the manual says some pinging when going uphill or on hot days while towing(which I experience none of) is ok.

So I guess my question is, why is the experience so drastically different with different fuels in different cars? Also, what's the deal with fuel grades? I've been told pinging is never ok, so are the car manufacturers just avoiding telling people the truth that some cars need 93 because they don't want it to become a negative selling point?

Thoughts anyone?

 

[MrSony]

I think there is something seriously wrong with that Colorado if it pings on 87. Most cars now with them fancy computers should adjust timing and engine parameters to basically run on anything combustible. Is it a 5 cyl? .

 

[oldmansmonte]

I think there is something seriously wrong with that Colorado if it pings on 87. Most cars now with them fancy computers should adjust timing and engine parameters to basically run on anything combustible. Is it a 5 cyl? .

Search Chevy Colorado pinging. The threads are literally endless. ENDLESS. Is there something wrong? In design but I don't think anything specific to mine. By 100k I'll tear the engine down and have everything cleaned. Till then it's 93.

 

[tkruger]

I have an 2004 Colorado with the I5. Use the lowest grade available and never had an issue. Currently it has about 110,000 on it. Used it for daily driving, towing, 4x4 etc. The one issue I have had was a dirty throttle body. Issue occurred twice early on when I had the truck. My mechanic advised me to run a bottle of Lucas cleaner in a tank every 1000 miles or so. Since I started doing that I have not had to clean the throttle body.

In my 1987 4.3 if there is ethanol in the gas then I have issues with the 87. I just run 89 or 91 then depending on the station. If it is ethonal free gas then 87 works.

 

[oldmansmonte]

I have an 2004 Colorado with the I5. Use the lowest grade available and never had an issue. Currently it has about 110,000 on it. Used it for daily driving, towing, 4x4 etc. The one issue I have had was a dirty throttle body. Issue occurred twice early on when I had the truck. My mechanic advised me to run a bottle of Lucas cleaner in a tank every 1000 miles or so. Since I started doing that I have not had to clean the throttle body.

In my 1987 4.3 if there is ethanol in the gas then I have issues with the 87. I just run 89 or 91 then depending on the station. If it is ethonal free gas then 87 works.

We have ethanol free 91 available at some places here. I do get an occasional ping with that. Nothing like 87 though.