Hello and annoying rattle on new '20 Suburban

[OR VietVet]

What octane does the owner's manual call for? If it calls for 87 and it pings then maybe you need to contact dealer and ask why it needs the higher octane to keep from pinging.

 

[Rdr854]

What octane does the owner's manual call for? If it calls for 87 and it pings then maybe you need to contact dealer and ask why it needs the higher octane to keep from pinging.

Exactly what I was thinking. If the OP has a 5.3 liter motor, then the owners manual will specify 87 octane gas.

 

[Miami-Dade]

Every 5.3 on the road should be okay on 87 octane. I tried 89&93 on a run up I-95 and saw zero difference in mileage or performance. I run almost nothing but 87 Mobil-Exxon as their stations are always well maintained.

When I go thru Maryland I stop at the Maryland House on I-95 and get their Sunoco fuel so I do not have to get off I-95. That tank will last me till I get into NYC and longer. That seems to work okay.

During a Hurricane a few years ago I was forced to use Shell as all other stations were out of fuel. The Florida Turnpike always has fuel 24/7 even in a nasty hurricane but the downside is it is Shell. Besides my mileage dropping in half it ran horribly.

How Shell makes the Top Tier Fuel list baffles me.

 

[iamdub]

The 87 vs. higher octane debate is longstanding at least since the GMT900 ('07-'14) model years. Yes, the owner's manual states a minimum of 87, but anyone "in the know" recommends 89 or higher. Most of those would also advise against Shell. My experience is very little to no knock with just stepping up to 89. I drive mine hard, so I run 93 or E85 exclusively. I have to now that it's tuned, but that's irrelevant here. I'm sure the newer engines have even higher compression and advanced timing, so lower octane and crap gasoline quality would be even more of a problem.

I'd stick to 89 or higher from Exxon or Chevron/Texaco. There are other good brands but those are my go-tos. If yours is FlexFuel (are they all now?), you could run E85 and it'd definitely not knock. It should have more power, too. It's cheap fuel, but returns poorer fuel economy. If it's worth it to you, you can mix 87 and E85 to strike a balance of best fuel economy, power and lowest cost. It's just a lot to calculate the cost per mile every time you need fuel since the prices and your intended use changes (normal city commute or highway trip, etc.).

 

[OR VietVet]

My 02 runs fine on the lower octane but I always use the middle octane, Chevron grade labeled "Plus". Performs great and has more additives that I feel help keep the fuel system clean.

 

[Miami-Dade]

My 02 runs fine on the lower octane but I always use the middle octane, Chevron grade labeled "Plus". Performs great and has more additives that I feel help keep the fuel system clean.

I thought the same way for years but my coworkers who had Cadillac's at the time all ran 87 with no issues with the fuel system. Some had a 90 minute commute each way on a good day. We all bought our Caddy when they were about 2 years old. I dropped down to 87 from 89 [Exxon] and had zero issues with the fuel system or anything else related to fuel. We all put way over 100K miles on them. Mostly highway but city miles on weekends. We all ran either Exxon-Mobil or Chevron.

To each their own.

 

[OR VietVet]

Yea, old people like me have old ways. I can't help myself.

 

[iamdub]

I would think that Exxon's 87 may be as good or better than Shell's 89. Gasoline varies by region and formulations change over the years and even seasons. Engines are considerably different as well with compression, ignition and fuel timing. So, whatever experience one may have had with a certain brand or octane grade in a past vehicle wouldn't be very relevant now. I'd have to assume that, across the board, fuels now aren't as good as they were a few years ago. About the only consistency I can see from my experiences is Shell is still lower quality. The way it's driven is a factor as well. Maybe the OP accelerates harder than some, putting more load on the engine. Maybe Gary and his coworkers with their Cadillacs were a little softer on the pedal, reducing the chance of preignition. Maybe they weren't, but the gasolines were better back then so it didn't matter.

Too many variables to compare "then" versus "now".

 

[Rdr854]

Modern vehicles are computer controlled to adjust for fuel octane and other factors. As a result, the recommendation is now to follow the octane rating recommended in the Owner’s Manual. Likewise, some OEMs may recommend Tier 1 gasoline when available.

It is important to note that Gasoline for use in motor vehicles is strictly regulated by the EPA, and as a result, must meet certain minimum standards. The following is from the EPA web site:


The Clean Air Act requires EPA to regulate fuels and fuel additives for use in motor vehicle, motor vehicle engine, or nonroad engine or nonroad vehicle if such fuel, fuel additive or any emission products causes or contributes to air or water pollution that may endanger the public health or welfare. EPA must also address emission products of such fuel or fuel additives that may impair any emission control devices used on vehicles or engines to reduce harmful emissions.

Gasoline regulations are under 40 CFR Part 80 (“Regulation of Fuels and Fuel Additives”): subparts A (general provisions, applying to all 40 CFR Part 890 fuels programs), B (controls and prohibitions), C (oxygenated gasoline), D & E (reformulated gasoline), G (detergent gasoline program), H & O (gasoline sulfur) and J & L (gasoline toxics).

 

[iamdub]

Modern vehicles are computer controlled to adjust for fuel octane and other factors. As a result, the recommendation is now to follow the octane rating recommended in the Owner’s Manual. Likewise, some OEMs may recommend Tier 1 gasoline when available.

It is important to note that Gasoline for use in motor vehicles is strictly regulated by the EPA, and as a result, must meet certain minimum standards. The following is from the EPA web site:


The Clean Air Act requires EPA to regulate fuels and fuel additives for use in motor vehicle, motor vehicle engine, or nonroad engine or nonroad vehicle if such fuel, fuel additive or any emission products causes or contributes to air or water pollution that may endanger the public health or welfare. EPA must also address emission products of such fuel or fuel additives that may impair any emission control devices used on vehicles or engines to reduce harmful emissions.

Gasoline regulations are under 40 CFR Part 80 (“Regulation of Fuels and Fuel Additives”): subparts A (general provisions, applying to all 40 CFR Part 890 fuels programs), B (controls and prohibitions), C (oxygenated gasoline), D & E (reformulated gasoline), G (detergent gasoline program), H & O (gasoline sulfur) and J & L (gasoline toxics).

I hear what you're saying, and I'm not one to challenge engineers unless it's an obvious shortcoming (which is usually understandably justifiable). But, when my engine knocks due to lower octane fuel, I don't give a damn what the owner's manual recommends or if the gasoline met anyone's minimum standard. The EPA can only regulate so much. They're not sampling every underground tank of every fuel station. On the other side of it, engineers are forced to compromise to meet some of the EPA's other, sometimes contradicting standards. Designing engines with higher compression and more aggressive ignition timing to increase power rather than more aggressive cam profiles and fueling maps narrows the range of acceptable fuel qualities and conditions for which it is safe to operate.