Regular vs Premium Unleaded?

[redhoghunter]

Tagged for after work reading

[bowhntrmatt]

My truck says 91 minimum in the owner's manual. So that is what it gets.

Wife's Tahoe says 87, so that's what it gets.

[FLASH_OUTDOORS]

I run regular in my Tundra, but my wife G-Wagon will only see Premium no matter what it costs.

Sent from my iPhone using Tapatalk Pro

[oktx]

I have a performance car that recommends 93. I only buy 1 tank about every month and a half because I only drive it on the weekends.

[Bayouboy]

i know on the ecoboost ford you have to run premium for a while for the computer to learn and adjust the fuel mapping accordingly... mixing 15 gallons of premium with 11 of regular may equate to mid grade overall ..

my new truck has 36 gallon tank ... i can't afford to fill it up with premium without getting a bank loan...

Where did you get that info? I have one and never heard that. I have run 87 in it since I bought it.

[oktx]

Where did you get that info? I have one and never heard that. I have run 87 in it since I bought it.

Our company pickups are ecoboost, we definitely don’t run 93. They would ****. LOL

[jaime1982]

I have a performance car that recommends 93. I only buy 1 tank about every month and a half because I only drive it on the weekends.

Our Lexus was a 12 compression ported engine that required higher octane to prevent auto-combustion. The fuel needs to be able to detonate at the correct compression ratio and timing. Every other vehicle we run regular.

I lol when people buy premium fuel for their lawn equipment because (its better)..

[91cavgt]

There is a misconception that premium fuel does not have ethanol in it. Sorry but it does. The ONLY way to get ethanol free fuel is to buy it from a pump that states ethanol free. I’ve seen some independent tests that showed some premium actually has more than 10% ethanol in it. One test showed just over 20%!!!!


In SOME high compression engines, premium will give you better fuel economy but this is not across the board. Cam timing plays a HUGE roll in cylinder pressures as well as static compression. I had a 2006 Chevy Colorado with the 2.8L 4 banger with 10.0:1 compression that would get 3-4 mpg better with 93 octane, so that’s what I ran in it even though it would run fine on 87. I ran tests on my SRT4 (turbocharged 2.4L) and found it could run up to 7 psi of boost without any decrease in ignition timing. For cruising this was fine, but 7 psi was a LOT lower than the 19 psi it would run with 93 octane. With that car, it was a HUGE performance difference(around 100 hp).


In my wife’s car, a 2019 VW Atlas with a 2.0L turbo motor, it runs fine on 87 octane so that’s what we run in it, unless we are towing with it. That’s when it gets 93 octane.

[oktx]

Our Lexus was a 12 compression ported engine that required higher octane to prevent auto-combustion. The fuel needs to be able to detonate at the correct compression ratio and timing. Every other vehicle we run regular.

I lol when people buy premium fuel for their lawn equipment because (its better)..

Does the premium fuel have less ethanol in it? I honestly don’t know. I appears it does contain ethanol.

[jdg13]

Does the premium fuel have less ethanol in it? I honestly don’t know.

It used to when ethanol first started being added. Now pretty much all pump gas is 10% unless it's ethanol free.

[McPatrickClan]

In the Yukon I have for sale in the TBH Classifieds I almost always ran premium and without question I noticed a performance boost. GMC suggests premium so that’s what I did. At Costco it is usually only a quarter or so more per gallon.

[WItoTX]

Where did you get that info? I have one and never heard that. I have run 87 in it since I bought it.

What he is saying is it takes the ECU a few tanks to fully shift into 93 octane mode because it takes a while to work out all the 87 octane fuel. Not that 93 is required.

[Mike D]

What he is saying is it takes the ECU a few tanks to fully shift into 93 octane mode because it takes a while to work out all the 87 octane fuel. Not that 93 is required.

That’s not how engine computers work. They react pretty much instantly to issues within the engine to prevent damage or optimize fuel economy.

We ain’t dealing with points & condensers here.


Sent from my iPhone using Tapatalk Pro

[Fordnandez]

What he is saying is it takes the ECU a few tanks to fully shift into 93 octane mode because it takes a while to work out all the 87 octane fuel. Not that 93 is required.

The performance cars that I know that strongly suggest higher octane fuel have knock sensonrs in them so they can detect early detonation. When this happens and my understanding that is is pretty instantaneious is that it the computer adjusts the timing which reduces performance. Not sure if this is the case on the ecoboost or not.

On my dads 2019 Ecoboost I looked in the manual and it does recommend 91 I believe, it was forsure over 87. With that said it has ran on 87 its whole life but we havent seen if 91 equates to better performance or fuel economy.

This was several years back when fuel was cheaper but my brothers Titan got so much better mileasge with premium that it out ran the cost of the fuel so he always put premuim in it.

[91cavgt]

The performance cars that I know that strongly suggest higher octane fuel have knock sensonrs in them so they can detect early detonation. When this happens and my understanding that is is pretty instantaneious is that it the computer adjusts the timing which reduces performance. Not sure if this is the case on the ecoboost or not.

On my dads 2019 Ecoboost I looked in the manual and it does recommend 91 I believe, it was forsure over 87. With that said it has ran on 87 its whole life but we havent seen if 91 equates to better performance or fuel economy.

This was several years back when fuel was cheaper but my brothers Titan got so much better mileasge with premium that it out ran the cost of the fuel so he always put premuim in it.

Yes, all of the ecoboost engines have knock sensors that will tell the computer if knock is detected. If knock is detected on those engines, not only will the timing be retarded, but the boost pressure will also be lowered. This goes for pretty much all factory turbocharged engines.


On my old SRT4 for example, with the factory computer controlling everything, if you ran 87 octane fuel then at the first sign of knock, ignition timing would be pulled back and the boost would lower from 13 psi down to 5 psi. After I played with it, I found the upper limit for 87 octane was 7 psi of boost, so the factory programming was conservative.