Jump to content

Recommended Posts

Posted

I use 89 octane at the advice of Blackbear tuning. They recommend at minimum using 89 octane even on STOCK tuning (for the 5.3 and 4.3). 6.2 motors should be using a minimum of 91.

Posted

I use regular 87 for daily driving and I use premium 91 for towing my 6000lbs camper... sometimes the boat too at 3500lbs, but not always... depends on how full tank already was... but only premium 91 in the boat or else it pings.

Unless you are tuned for the higher octane or have the 6.2L engine, you are wasting your money filling up with 91 octane. Putting higher octane in your truck because you are towing something will not help with anything but making your wallet lighter.

 

 

Sent from my crappy iPhone 6

using Tapatalk

Posted

I use 89 octane at the advice of Blackbear tuning. They recommend at minimum using 89 octane even on STOCK tuning (for the 5.3 and 4.3). 6.2 motors should be using a minimum of 91.

That must have been you that I heard that from. Why did he recommend 89? Was it due to what he was seeing via engine knock sensors? My thoughts are that perhaps it was with 87 he saw some knock retarding happening while 89 was just enough to avoid it and 92+ wasn't necessary?

  • Like 1
Posted (edited)

89. These engines have to high of a compression ration to run the cheap stuff.

Edited by haider320
  • Like 3
Posted

I ran several tanks over two months with 93 and saw absolutely no difference from 87. Now I stick with 87 and save ~$10 a tank.

  • Like 2
Posted

I use 87 exclusively and only fill up at Shell, BP, Chevron, or Mobil. My lifetime average fuel economy is 18.1 mpg for 8,000 miles. My typical highway economy is 21 mpg. I cannot run e85 because my 2015 engine is not compatible.

Posted

E85 or mid grade gas. E85 locally mid grade on trips.

 

 

Sent from my iPhone using Tapatalk

Posted

The 5.3 can get by with 87 but I bet it will show better numbers with 89 over the long run, the 6.2 with approximately 11.5:1 compression needs the good stuff, 93 octane is all my truck sees.

Posted

Unless you are tuned for the higher octane or have the 6.2L engine, you are wasting your money filling up with 91 octane. Putting higher octane in your truck because you are towing something will not help with anything but making your wallet lighter.

 

 

Sent from my crappy iPhone 6

using Tapatalk

It won't get me any better fuel economy and certainly costs me more, all true... but has better additives and runs cooler. It's worth the extra $$$ to run cooler when towing to me.

Posted (edited)

I have the 6.2 so I run 92 or 93 depending on where I gas up.

Edited by Last C5
Posted (edited)

E85 or mid grade gas. E85 locally mid grade on trips.

 

 

Sent from my iPhone using Tapatalk

This.

 

I average around 18-18.5 with e85 and 20.5-21 with 89. Financially it doesn't make any since to run regular gas as long as I can find e85.

Edited by Stars_Fan
Posted

E85 or mid grade gas. E85 locally mid grade on trips.

 

 

Sent from my iPhone using Tapatalk

 

Same thing here! Except I only use e85 when home and use gas when I go up north. I wonder if the motor will ever have long term effects with using roughly 95% of my fuel being e85. Thats what a warranty is for.

Posted

This.

 

I average around 18-18.5 with e85 and 20.5-21 with 89. Financially it doesn't make any since to run regular gas as long as I can find e85.

I pay between 1.35-1.65 for E 85, even if was the same price as mid grade gas Id buy it for the extra HP. I only use gas when I can't get E85 traveling.

 

 

Sent from my iPhone using Tapatalk

Posted

It won't get me any better fuel economy and certainly costs me more, all true... but has better additives and runs cooler. It's worth the extra $$$ to run cooler when towing to me.

This has me confused, can you explain why it would run cooler?

Posted

Ethanol burns cooler than gas, but your engine has to burn more e85 which makes it run hotter than burning gas.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Latest Articles

  • Posts

    • My 2025 Silverado 1500 had to receive a brand-new engine (long block) under warranty last month at only around 16,500 miles. Before the replacement, the truck repeatedly displayed "Engine Oil Level Low" warnings, even though the Oil Life Monitor still showed around 50% remaining after about 6,000 miles since my last oil change. After seeing the warning several times, I checked the dipstick with the engine cold, and the oil level was completely normal. The next day, the message escalated to "Add Engine Oil." At first, I assumed it was just a faulty oil level sensor, so I brought the truck to the dealership. After inspecting the engine, they found internal cylinder wall scoring and ultimately replaced the entire long block under warranty. Before this happened, I was planning to install a 4-inch lift and suspension upgrade on my truck. After needing a new engine at just 16,500 miles, I honestly don't see the point anymore. I also contacted GM to ask whether my vehicle qualified for a buyback, but I was informed that it does not at this time. Anyway, this experience has left me with serious concerns about the long-term reliability of this engine. I sincerely hope NHTSA expands the current investigation or recall to include 2025 model and performs a thorough inspection of affected vehicles. My biggest concern is that these engines may fail shortly after the powertrain warranty expires. If GM truly stands behind this engine, then at the very least, please consider extending the powertrain warranty to 10 years for affected owners. That would go a long way toward restoring customer confidence.
    • Without exception but then I'm the odd duck, right? I know what goes into that test, how it is calculated and thus how to beat it. But EPA values are often not beaten by the general public and the government has in past years adjusted the means and methods to come to those values to more closely approximate "Joe Average".    The only real trick to beating that EPA average is don't drive like "Joe Average".    It's the same method you used to profit from "Economic Migration" and in doing so beat the 'stats'. But you, like me, are not "Joe Average".     The thing you don't seem to grasp is this "Purchasing Power Index" isn't forward looking. It doesn't predict what it going to be but looks backward and states what it was. They are not telling us what the THINK, they are telling us what they MEASURED. Example:    Wife says "I'm going to lose 40 pounds by Christmas". May she does, maybe she doesn't but the doctors office who weighed her when she made that statement and again at Christmas only REPORTS what the RESULT was. You and I can banter about what was possible and what aunt Tilly did till the cows come home but the result is the result. Arguing otherwise is.....irrational. That's all I'm saying. This isn't about:      What you are calling a 'Statistic' is a RESULT not a CALCUATION and as a result the RULE. Like gravity as a rule, it can not be broken. 
    • Just wanted to say thank you for posting this. Years later, your thread is still helping Silverado owners.   I bought my 2025 Silverado 1500 in January 2025, and I've had what feels like the exact same rattle since day one. After reading your findings, I believe my truck has the same issue with the cable carrier contacting the rear sliding window. To be honest, I had pretty much given up on pursuing the issue. It wasn't until I recently drove another brand's pickup that I realized just how quiet their cabin was—and how noisy mine has been all along. On my truck, the rattle happens on almost any paved road, gets even worse on rougher pavement, and I can even hear it during braking and acceleration.   I actually referenced your thread when submitting my case to GM, hoping they'll recognize this as a recurring issue instead of treating it as an isolated incident. The reason I reached out to GM first is because my dealership told me they would need to keep the truck for at least two days just to diagnose the problem. I was concerned that even after two days, they still might not be able to identify the source of the rattle before giving the truck back to me. I had also asked a few dealerships about this issue during previous service visits, but none of them seemed to know what was causing it or had a solution. That's why I decided to contact GM directly first, hoping they might already have an official repair procedure or guidance for this issue.   I also hope GM eventually comes up with an official fix for this problem. I have a feeling there are many Silverado owners experiencing the same rattle, but most either choose to live with it or simply don't know what the cause is.   Really appreciate you taking the time to document your diagnosis. Your post is still making a difference years later.
    • I have 2 choices. 
    • Do you have access to BP fuels? Some stations have Silver 91 E-0 priced the same as their 93 E-10.  There is a local Marathon with 90 alky free for $6 a gallon but I go down the road to BP for $5-ish. They also have a 100 E-0 but that stuff is $10 a pop. 
  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...