Super Unleaded

[FreeAmerican]

From what I recall/ my truck is at the dealership for repairs so I can't check right now right now, it was regular unleaded for the 5.3 and IF I remember correctly if not please correct me if I'm wrong, the 6.2l was premium. That's the little I remember from my owners manual. When I purchased the truck I forgot to ask the sales person what octane level to use on my new truck. I checked on the owners Manual and I recall regula for the 5.3 but I will check and have no issue admitting I'm wrong on what I recalled from the book

You are not wrong at all. Like 07Softail said, GM knew better than to require their bread and butter truck engine to use higher than 87 I am sure when shopping for a truck, One requiring more expensive gas would be deal breaker for some.

 

And you aren't getting cheated, that's what they used get the HP / Tq / mpg ratings.

 

But the electronics of the engine will take advantage of the higher octane.

[Amuro]

You are not wrong at all. Like 07Softail said, GM knew better than to require their bread and butter truck engine to use higher than 87 I am sure when shopping for a truck, One requiring more expensive gas would be deal breaker for some.

 

And you aren't getting cheated, that's what they used get the HP / Tq / mpg ratings.

 

But the electronics of the engine will take advantage of the higher octane.

I think I might be wrong. I'm sure you and I have the same manual, if the book states that 87 OR higher then that part flew over my head because the key word I looked at and remember was regular unleaded and to me means the cheap stuff 87 lol! Now I know I can also use mid grade or premium if I like.

 

So this engine wouldn't work for what I was trying to get at, let's say a engine/ the owners Manual states regular only 87 period then using premium wouldn't be beneficial to the engine and a waste of money due to the fact it's tuned and designe to run on regular 87 and ours is designed to run on all 3! Learn something new about my truck!

[Cowpie]

Find, if one can, a reference that the engine as it comes from the factory to use regular 87 will take advantage of higher octane fuel from this part of my owners manual. It does say 87 or higher, but nothing about that it will take advantage of higher octane. It does say to not use less than 87. Only the 6.2 has a reference to premium, but regular can be used but switch to premium when available. This idea that GM just says to use 87 so they could sell more vehicles and the engine (non 6.2 variety) really can take advantage of higher octane sounds more like internet folklore.

 

 

[KARNUT]

There has been many claims by tuners on here that the 5.3 performs better on higher grades of gas. More KR events on lower grade. Doesn't say you can't use lower grade or should use higher, just explains the results. Most driver wouldn't care, some driver want max performance.

[Cowpie]

I think the key word you use is "tuners". Folks start playing around with the ECM settings and, yes, I can believe that 87 might not be sufficient. It does beg the question in this, if premium will deliver max performance, and they claim they need that, then why wouldn't that person just buy a pickup to begin with that gives them the performance they need? If they have a 5.3L and they need to tweak more performance out of it, then why didn't they just get a 6.2L to begin with? If I go hunting in Alaska and find that a .243 is not sufficient to bring down a 1500 lb moose every time, I don't tweak the powder on reloads to get more performance from the cartridge. I instead move on to a .338 that has the capability I need right out of the box.

[KARNUT]

They were stating during their data log that there is more KR with reg gas and mid grad gas was preferred in a untuned engine. I used E-85 in town and reg on trips.

[HoosierZ]

I'm not too confident in GM's tuning or fuel specs. I had a 2013 Malibu with the 2.0 Turbo. About a year after buying it, GM issued a recall to inspect the pistons for damage, change to a colder spark plug, and reprogram of the ECU. That tells me there was an issue with predetonation. It also called for 87 octane which I thought seemed odd for a forced induction engine. After the recall it always got 89 as a safety cushion.

 

I know two people with Cruze turbo cars who both had engine issues. One had the pistons replaced and the car was in the shop to have the head replaced when GM bought the car back.

[Cowpie]

I can see the idea of higher octane with forced induction engine. By it's very nature, compression is going to be higher. But that is not the case with what we have been discussing here. More times than not, a naturally aspirated engine that was designed with 87 in mind that then needs a higher octane to overcome knock events, has carbon buildup issues in the cylinder, specifically on the piston crown. That has been the case from back in the carbureted days of engines and still holds true today. A bandaid on the problem as opposed to correcting it. The vast majority of 5.3 owners continue to use 87 and do not deal with any issues. Fleets that have 5.3's in their 1500's as well. Only a few people, sporadically, deal with this sort of thing. That speaks more, again, to carbon buildup, poor gasoline buying, etc as where the problem lies, else there would be a track record of some statistical average of 5.3L engines having issues, and you would start seeing major articles in auto oriented magazines addressing the problem. Keep in mind, out of the number of folks that have these pickups, only a thimbleful of them are on any forums discussing them.

[sdeeter19555]

Just for giggles I have ran the last four fills, because of the two or three recent threads on the subject, with 87 from a top tier station. I've been putzing around a Navy facility for the past four or five days, so mileage is anyone's guess.

 

But I noticed two things right away...my surging is back, my surging is now associated with pinging, and it has a little shake at idle.

 

Otherwise, it drives down the road...

 

Sent from my SAMSUNG-SM-G900A using Tapatalk

[KARNUT]

Some people call driving a ends to a means, some people call driving an event. The event drivers want their vehicles to perform, the ends to a means drivers just get me there. They wouldn't notice a little pinging reduced performance, the event drivers notice everything in driving. There're the data loggers and testers I'm one of those. I ran reg gas on HWY trips, in town E85 or mid grade I noticed the difference. My wife not so much.

I can see the idea of higher octane with forced induction engine. By it's very nature, compression is going to be higher. But that is not the case with what we have been discussing here. More times than not, a naturally aspirated engine that was designed with 87 in mind that then needs a higher octane to overcome knock events, has carbon buildup issues in the cylinder, specifically on the piston crown. That has been the case from back in the carbureted days of engines and still holds true today. A bandaid on the problem as opposed to correcting it. The vast majority of 5.3 owners continue to use 87 and do not deal with any issues. Fleets that have 5.3's in their 1500's as well. Only a few people, sporadically, deal with this sort of thing. That speaks more, again, to carbon buildup, poor gasoline buying, etc as where the problem lies, else there would be a track record of some statistical average of 5.3L engines having issues, and you would start seeing major articles in auto oriented magazines addressing the problem. Keep in mind, out of the number of folks that have these pickups, only a thimbleful of them are on any forums discussing them.

[Cowpie]

Ok. Decided to go down this rabbit trail.

 

Premium is going to run 30-50 cents more tha regular in most areas. I can buy a case of 12 bottles of octane booster for $22.56, or roughly $1.90 a bottle that will treat 20 gallons of gas and raise it to 91 octane for about 9.5 cents per gallon.

 

9.5 cents vs 30-50 cents. And why would I want to buy premium? For those solidly in the "better to use high octane" camp, seems like a more cost effective approach. Kinda shocked no one else took the time to run the numbers.

[TJay74]

Octane booster in a bottle has been shown and proven many times over the years to not raise octane nearly as high as the bottle suggest. Last test I read years ago showed it was lucky to raise an entire tank of gas 1/2 of 1 point. So it would take 87 to 87.5. That is not worth it at all.

[Black02Silverado]

I found this information interesting from Lingenfelter when they did some dyno runs with the new 5.3 engine: "Also, two of four gasoline runs showed knock during the acceleration test (including the fastest run). Neither of the E85 runs showed knock during the acceleration tests (only did 2 runs with E85 since they were so similar). Interesting to note that when not at high throttle angles the ECM shows a lot of knock with either fuel."

 

Source: http://www.lingenfelter.com/forum_lingenfelter/forum/lingenfelter-forum/general-motors-suv-trucks/1245-2014-1500-silverado-with-5-3l-l83-engine-work-begins

 

I have a 5.3 and with my ScanGauge I can monitor KR (knock retard) and timing advance. I notice the most KR when running 87. It usually shows up at low RPM's with increased engine loads (example: going up a hill/incline with cruise set). V4 mode is particularly sensitive to KR. E85 all but eliminates any KR and timing advance is noticeably higher when cruising (especially in V4 mode)

 

I try to run 89 as much as I can. Usually it's only 10-15 cents more a gallon then 87. Some stations eve have it priced the same. I will occasionally run 91 if it's on that much more then 89. Where I live 91 octane is usually ethanol free which makes it more expensive (around 50 cents a gallon over 87 octane).

 

From what I have gathered (at least with my vehicle) is that the engine is sensitive to octane levels. Can it run on 87? Absolutely but it's right on the edge of developing KR and pulling timing back. Running 89 doesn't cost that much more in the long run and provides a little cushion to KR. Every engine is different so results will vary but from what I have seen I'll stick with 89 minimum.

Good info. I also was told by Black Bear Performance to run 89. Justin said that these new engines have a higher compression and can see better performance, ie less detonation running 89. Now if you are tuned then run what you need to per the tune. Also E85 is around 100 octane, so if you mix it with regular you can get the benefits of higher octane, less cost and cleaner burning engine.

[KARNUT]

Ive read lots of good post from you and you know your stuff. I know because I built, sold service all kinds of diesel powered equipment. Just because some people think running a higher grade of gas is price worth paying doesn't make it a rabbit hole. I could get E-85 at a reasonable price and the performance was notable. Even it cost me more the performance was worth it. The people who run higher grades of gas felt the difference and data logs showed why ( KR ). Few dollars more, ok skip the Starbucks take your own coffee.

 

Ok. Decided to go down this rabbit trail.

 

Premium is going to run 30-50 cents more tha regular in most areas. I can buy a case of 12 bottles of octane booster for $22.56, or roughly $1.90 a bottle that will treat 20 gallons of gas and raise it to 91 octane for about 9.5 cents per gallon.

 

9.5 cents vs 30-50 cents. And why would I want to buy premium? For those solidly in the "better to use high octane" camp, seems like a more cost effective approach. Kinda shocked no one else took the time to run the numbers.

[Cowpie]

I said "rabbit trail" not rabbit hole. Rabbit trail is a debate term for following a discussion wherever it leads. I decided to follow the pro octane rabbit trail and offer an alternative proposition to spending more than folks need to to get the result they want. I wasn't aware that it was offensive to help others save money.