premium gas in a 5.3L (GMT900)

[j-ten-ner]

A few weeks ago I decided to fill up the tank with Premium gas. Can't even remember why. Maybe just for the fun of it.

I'm on the 3rd tank now.

 

First, my truck did not become a high performance car.

But, the acceleration is way smoother. And that makes it feel like the truck gained some balls.

I think it is due to the higher octane and that the ignition does not dial back so much to prevent knocking.

 

What's even better, the transmission seems to be more confident that the motor can handle the gear it is in.

Going uphill the trans is holding the gear much longer or doesn't down shift at all. Reduced gear hunting.

I'm driving the same routes on a regular basis, so I can tell the difference.

 

Over all, the truck drives much better. Not so sluggish but more sturdy, if you know what I mean.

 

Is it worth it?

With my very conservative driving style (I call it confident driving style, btw ) I can feel a gain in more comfort of driving.

Some may say "why don't get a 6.2 instead when you fill up premium anyway?"

Well, with the 5.3 I can go back to regular when ever I feel like it.

Hell, I could even step up the game one more notch and fill it up with Ethanol.

 

so long

j-ten-ner

[5proms]

I would suggest at least at a minimum a Bully Dog Tune to optimize for Premium gas. A low cost way to reprogram the computer, plus it will allow you to reprogram back to regular.

[POS VETT]

You're not imagining things. It's worth the extra price for me. I blend in E85 in low amount to bolster the effective octane number.

[j-ten-ner]

I'd love to try E85.

But the next gas station (and the only one, as far as I know) is in West Vancouver.

That's about 60km one way from my place...

 

There is one spot in particular where I can experience the benefits the best.

When I turn the corner leading to the street I'm living at, there is a small hill.

When I don't have to stop for the oncoming traffic, the speed is fast enough that the truck stays in the 3. gear.

And exactly at the moment when the little hill starts, the converter clutch engages.

Before I've tried the Premium fuel, the truck fell on his face.

Now he keeps pulling.

 

so long

j-ten-ner

[white1500]

I have a dinosaur but I only run 91, she really likes it too!

 

Although Costco only has 87 or 91, and I sure as hell am not going to cheap out.

[Colossus]

The newer trucks are tuned to respond a bit better to the higher octane. GM and other automakers will list the lowest octane the truck can safely operate on (at sea level) for EPA/fuel economy/buyer interest reasons, but I too noticed the same things you did by running premium (91 Octane up here at 6000ft) vs the 85 Octane (which is 87 down at sea level) in my 2013 Impala. The thing already had some balls with the 305 HP DI 6 Cylinder, but it was much more responsive with the 91 and the few times I ran E85 in it.

[CadillacLuke24]

If you like the drive ability improvement, I say go for it.

 

Never expected it to have an improvement going up in octane. I know going down causes issues...been there done that with the Caddy.

 

Glad to hear it works for you

[5proms]

I keep my 5.3 L59 'flashed' for 91 octane or better and always try to use 'Top Tier' fuel. AMSOIL products in the crankcase and tranny, 210,000 miles and counting.

[swathdiver]

For thirty some years and dozens of vehicles this has been proven true for me. Top Tier 93 octane has nearly always given a 2+mpg edge over the cheap stuff and with all the benefits mentioned in the OP.

[Crazyfly]

I've always put 91 in my truck since I've bought her

 

 

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[sdeeter19555]

Running 91 or 93 makes a significant difference in my 6.0l...you should try towing heavy on 91/93 versus 87.

 

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[Z45]

All the information out there tells you to the contrary, use premium gas does not increase fuel mileage. Those claiming it does are only trying to justify the added cost in their minds.

 

Opinions are not facts

 

 

If your car does not require premium gas, there are no added benefits to your car’s performance or longevity. Simply put, you’re paying good money for something you don’t need. Premium costs 15-30 cents more a gallon than regular. In a consumer notice, the Federal Trade Commission, notes: “In most cases, using a higher-octane gasoline than your owner’s manual recommends offers absolutely no benefit. It won’t make your car perform better, go faster, get better mileage or run cleaner.” Enough said.

 

[Sierra 5.3]

All the information out there tells you to the contrary, use premium gas does not increase fuel mileage. Those claiming it does are only trying to justify the added cost in their minds.

 

Opinions are not facts

 

 

 

http://www.roadandtrack.com/new-cars/car-technology/news/a18008/premium-fuel-futures/

 

"If the engine is tuned for regular but fueled with something of higher octane, things are a tad more complex. Most modern knock-sensed ignitions seek MBT timing and thus, at least in theory, profit from the added octane. Some, though, have preset ceilings beyond which they won't advance."

 

"What of midgrade? There's logic involving "legacy vehicles," older high-mileage machinery designed for regular. Even in these days of unleaded fuel, other combustion byproducts can cause deposits in the chamber that may increase octane appetite just a bit. The added octane of midgrade (blended at the pump from the station's premium and regular) might be just enough to counter this."

 

"Another interesting factoid, albeit one that's a bit contorted: Premium fuel is good for a catalytic converter. In allowing advanced timing of ignition, the fuel has a longer burn duration. This in turn gives more time for heat transfer within the combustion chamber—which results in reduced temperature of exhaust gases. This cooler "engine-out" condition makes for an easier thermal life of downstream catalysts."

 

.......who knows.

[MaverickZ71]

My 5.3L (LC9 flex fuel, but I've never run E85 in it) runs SO much better on premium these days. Like a complete night and day difference, on the factory stock tune. [i tried the Hypertech premium tune--all it did was make the truck shift bad, so I went back to the stock tune with AFM turned off.]

 

On the stock tune running premium, it idles smoother, accelerates better, shifts better, etc. And it wasn't knocking before because of low octane on regular or anything like that.

 

I've read where even the so-called 'top tier' stations aren't running the required levels of detergent or additives in their cheaper gas anymore, to save money (and nobody ever tests that, so they can get by with it); they just put in in their premium, because supposedly the only one making any money off of fuel sales anymore is the government with their high taxes. After noticing how my truck is running the last couple of years, I believe it.

[swathdiver]

All the information out there tells you to the contrary, use premium gas does not increase fuel mileage. Those claiming it does are only trying to justify the added cost in their minds.

 

Opinions are not facts

 

 

 

 

Quite the contrary, it usually costs more to run the cheap gas. As it stands now because fuel prices have come, it does cost a fifteenth of a penny more per gallon to run 93 compared with 87.

 

As for me, my conclusions are based on facts, thirty years worth.