2GR-FKS (3.5L) detailed layout

They use the same detergent package in all gas blends so difference in how it burns doesn't really matter much anymore. Plus the same refining unit can create multiple octane rated fuels at the same time. The only difference between the two would be the length of the hydrocarbon chains in both products. They'd have all the same characteristics otherwise since they went through the same process.

 

all 91 here, around 21/gal combined

 

Sadly, those "old timers" you've been listening to don't know what in the hell they are talking about.

Source

 

There have been many studies on this, and a YouTube video that was conducted.

Cars actually ran worse with higher emissions with the higher octane fuels

 

There's a bigger difference between E10 fuel and ethanol free than there is between 87 and higher octane gases.

 

I am not making an argument for higher octane BUT......What does "87 or higher" mean? I have never seen that in any of our vehicles.

The takeaway for that for me is this engine is capable of tuning itself for higher Octane.

I do not see 87 "or better' for the CRV, I run premium in the MX 5.

I exclusively use Costco 87/93 and getting 21 MPG avg since new

 

It's saying it will be fine on any grade rated 87 or above. It's generally accepted you can put higher octane fuel into an engine(to an extent) and be fine. However the inverse causes issues much more quickly. IE: 91 octane into an engine designed for 87 will likely have less issues than 87 octane going into an engine designed for 91.

You don't want to be putting AV Gas into an engine only designed for 87.

 

Being a more stable fuel it could allow for better operation in less than optimal conditions, IE hot or under significant stress. If an engine detects knock it will adjust timing to reduce the chances of detention. This adjusting timing will reduce power and fuel economy. How this pans out in this engine I don't know but that's the idea behind it.

 

You're not going to have stability differences in different octanes. Both would break down at the same rate.

 

One of the guys I knew in college put diesel in his gasoline motor one time. Toasted the engine and ended up costing something like 8k to replace it. I figured it was karma since he was intoxicated and driving.

 

I thought the diesel nozzle is larger than the gas nozzle so it doesn't even physically fit in the fill pipe.

 

I wasn't there when he filled the vehicle, I just got a call at 11 PM asking me if I can come help him out. I showed up asked what happened, and then asked if he put in his normal gas and everything, he said he used the green one and instantly knew what happened. Dude was a drunk jack ass who then tried to get me to stay with his car on the side of the freeway while he walked away to the party he was trying to go to so he wouldn't get a DUI. I just left his car on the side of the freeway and cut out contact with him. Made my life much easier than putting up with that stupidity.

 

I don't know where you get your refining info, but it is totally incorrect. By refining unit I guess you mean process unit, and there is no common process unit in the US that makes multiple octane products at the same time. There are only units that make a gasoline blending stock of usually fixed octane, and another unit (Reformer) that produces a variable octane (though only a given octane at any time). These products from the process units are sent to the tank farm for blending and final sales. The Reformer product (reformate) is blended with the other blend stocks to produce a finished tank of gasoline at whatever octane is specced.

Also added at the sales rack is the detergent. There is minimum amount required by law, so by and large there are not huge differences across the nation, but that is only a minimum. The big brands use more (and allegedly better) detergents in their top tier products. For example at the Shell stations around here only the premium 91 has their V Power additive. The 87 and 85 don't, and it is probably safe to say they have same detergent at the mandated minimum level.

Whether or not an engine benefits from a higher octane is different for every engine, you'll just have to see for yourself. Engine load and age will also have an effect. If it were naturally aspirated premium might not be economical, so I wouldn't use it unless I was towing a lot. If it were a turbo motor, I'd probably always use premium if that is what the manufacturer specs, since chances of detonation are higher.

So it depends on the motor and the circumstances. What I do know is that making a blanket statement of them being the same is simply not true. Do you really think manufacturers want multiple fuels if they all perform the same? And refiners would be fine running incredibly expensive Reformers for the sole purpose of making unneeded high octane gas?

 

While your correct they create blending components, units can create multiple components that only differ in octane rating. I work in a Hydrocracker and we create a blending component equal to about 85 and 90. The only difference is the size of the hydrocarbon chains. It will have the same sulfur/nitrogen content, corrosiveness, aromatic saturation, etc.

I also never said they'd be exactly the same. I clearly stated the difference is the length of the hydrocarbon chains which is the biggest factor in determining the octane rating. I didn't feel like breaking it down to the minute details because someone would probably point out some insignificant fact and think that magically means 91 has to be run in everything when it's clearly not true.

 

I'm not sure what multiple octane products from a single process unit even has to do with the topic, just that your generalized statement would be misleading to any reader until you qualified it in your last post. Clearer now, still not relevant though.

91 being required in everything is clearly not true, but your comments are awfully close to saying it means nothing, also not true. It depends.

BTW even in a hydrocracker I would guess (we don't have one) the octane is determined not by the chain length specifically, but shape? More aromatics (ring shaped) versus straight chain (paraffins and olefins)?

 

Hydrocrackers produce very few olefins and lots of paraffins whether cyclic or straight chain.

You straight up said said refining units only make single blending components of what's usually a fixed octane. I was just showing that some units can produce several grades simultaneously. If you read from who I quoted to the end I was pointing out why the assertion that higher octane=cleaner burning is incorrect. The detergent package cleans a lot of the motor and with how tightly regulated most parameters of gasoline are the difference in burn quality and leaving deposits on your engine is negligible between 87 and 91. You've got to read the thread with context if you're going to try to interject.

 

Seemed to me the discussion was mostly about mileage, not engine deposits.