[Mid_Life_Crisis]

Loving this car still as much as when I first brought her home a few years ago. I must say this V6 is a blast to run the gears. Most all of my miles are country side roads with extended runs between 5-6k rpm's. I don't baby her. I get the oil temp up to 215+ degrees every day and only run Top Tier 87 octane gas. Never burns oil as far as I can tell. I've used Royal Purple, Penzoil Ultra, and Mobil 1 EP and can't tell any difference between them. Oil changes at 5k miles. I think GM finally got things right with the LGX. It's sad they killed it.


I have the NPP exhaust and it sounds very good with a nice growl....really rips when on the gas! I don't like the rasp when in Sport mode if you press the pedal to the floor.....wish I could set the exhaust valves to not open all the way so it doesn't do this. That's mu only complaint about this system.


I'm getting every last drop out of the stock nun-flat tires.....there's still plenty of tread left. I run them at around 33lbs. When they're shot, I'll replace them with Continental DWS Extreme Contact all season. I hear they are great. I may try and score some ebay SS wheels for the rear so I can go 275 in the back. That will be mostly for looks. We'll see.


Anyway, very happy with this car!

[lowke]

Beautiful car. When you replace the run flats you will wonder why you kept them so long .I put 28k miles on my runflats , been on non run flat summer tires ever since. The v6 is to soft so I got Bilstein B6 dampers put on. My best mod was replacing the factory 20-8.5 ,30 lb wheels with 18-9 , 19.25 lb rotary forged wheels and 255-45-18 tires. Incredible improvement in everything about driving. Use premium top tier . Lgx will retard timing on 87. It may take a few tanks for the ECU to fully adjust.

[Mid_Life_Crisis]

Originally Posted by lowke

Beautiful car. When you replace the run flats you will wonder why you kept them so long .I put 28k miles on my runflats , been on non run flat summer tires ever since. The v6 is to soft so I got Bilstein B6 dampers put on. My best mod was replacing the factory 20-8.5 ,30 lb wheels with 18-9 , 19.25 lb rotary forged wheels and 255-45-18 tires. Incredible improvement in everything about driving. Use premium top tier . Lgx will retard timing on 87. It may take a few tanks for the ECU to fully adjust.

I'd love to get lighter wheels and also get mild lowering springs or coilovers but pretty sure I'm not going to spend that kind of money. I'd also love to get a Procharger but that's not going to happen either. Both would transform the car into mayhem in the twisties though.

[lowke]

I would not mod the engine it feels radical stock. I think wheels that weigh 20 lbs or less will be a great benefit. 255-45-18 is enough tire for me. I like a square set up

[lowke]

[bishopts]

I would run 93 octane. Its rated to be able to run on 87 but at 11.5:1 compression ratio it will be better.

[Mid_Life_Crisis]

Originally Posted by bishopts

I would run 93 octane. Its rated to be able to run on 87 but at 11.5:1 compression ratio it will be better.

I tried 93 octane for two weeks (two fill-ups) and noticed nothing different. This was during the heat of the summer. I'm fine staying with the 87 and save some money each week. The manual says nothing (that I could find) about adaptive ECU and adding more timing for 93. I've never had any pinging issues either.

[bishopts]

Originally Posted by Mid_Life_Crisis

I tried 93 octane for two weeks (two fill-ups) and noticed nothing different. This was during the heat of the summer. I'm fine staying with the 87 and save some money each week. The manual says nothing (that I could find) about adaptive ECU and adding more timing for 93. I've never had any pinging issues either.

All modern ECMs are adaptive. And it definitely pulls timing to run 87. But it's not the end of the world. It will "still run" on 87 it will just do do it better on 93. If your budget is so tight that you can't then don't. I would just suggest 93 because of the compression ratio. If you have the ability to get it setup for e85 it would do even better because of the compression ratio. Just like how our 6.2 cars do.

[lowke]

I got mine new and used 87 only till about 18k miles. When I ran it hard I would get a bad smell from the exhaust and was not running as well as before. It was like this for a few thousand miles.So I researched and started using 93. After a little while the smell stopped and began running great. I'm at 83k miles and have used only 93 since. I don't care what anyone uses, just telling my experience.

[Mid_Life_Crisis]

I'll try the 93 again this spring and see if I notice anything beneficial.

[dpevans]

Originally Posted by Mid_Life_Crisis

I tried 93 octane for two weeks (two fill-ups) and noticed nothing different. This was during the heat of the summer. I'm fine staying with the 87 and save some money each week. The manual says nothing (that I could find) about adaptive ECU and adding more timing for 93. I've never had any pinging issues either.

Running a higher octane is a waste of money, I never had an issue running 87 or 89. Higher octane fuel has the same amount of energy but is used to retard knock. If I didn't track my car I would have kept my V6 LGX instead of upgrading to the SS 1LE. The cost in ownership is higher. Much higher.

[bishopts]

Originally Posted by dpevans

Running a higher octane is a waste of money, I never had an issue running 87 or 89. Higher octane fuel has the same amount of energy but is used to retard knock. If I didn't track my car I would have kept my V6 LGX instead of upgrading to the SS 1LE. The cost in ownership is higher. Much higher.

Since you don't actually know what you're talking about. Let me break it down for you.

Higher octane fuel does not retard knock. That's like saying the mascot is the reason the net is on the field.

Before the piston is at top dead center, fuel is injected into the cylinder to alow it to mix with the air in the cylinder. Once the piston is at TDC the spark plug sets the mix on fire to maximize the total distance the piston is being pushed down. Throw in the fact that you need account for rotational velocity you will need to advance when the spark plug does its thing. That's where you see things like 10 degrees before TDC.

If you throw in low octane fuel then you have fuel that wants to ignite before its supposed to or at the first hint of spark. So when you're at 10 degrees before TDC it ignites and the piston is still in its upstroke so it ends up trying to push the crankshaft backwards against its forward movement. Thats called pinging (pre-ignition) which is a spark knock. So to account for your poor choice in fuel the PCM will see the pinging in its knock sensors and retard timing in an attempt to control the spark knock. So it will reduce engine performance especially at higher RPM.

So again it "will run" on 87 but you're running slightly under power to do so.
If you datalog your car you will see it pulling timing higher up when things are happening faster.

[Matt1LE]

Originally Posted by dpevans

Running a higher octane is a waste of money, I never had an issue running 87 or 89. Higher octane fuel has the same amount of energy but is used to retard knock. If I didn't track my car I would have kept my V6 LGX instead of upgrading to the SS 1LE. The cost in ownership is higher. Much higher.

There's been so many discussions on this topic and how the high compression of the LGX engine works best on high octane.


Not trolling, or being a "D", but if really want to know reach out to Tracy Lewis Performance. He's the LGX guru and covered this topic many times. He goes into detail why the LGX engine needs high octane.

[Mid_Life_Crisis]

Update.....I went ahead and tried some 93 in my car.....waited until tank was nearly empty of the 87 and filled it up. About $10 extra on the fill. I drove it pretty mellow for about 50 miles to allow the ECU to calibrate to the higher octane and then started to get on it at different driving speeds from full stop to 30-80 mph runs, etc. I have to say, I'm now a believer. The motor clearly has more pulling power. Everywhere. I can feel it. I'm not saying I'm going to keep going with the 93 all the time, but it's good to know it opens up some more timing for extra fun.