87 Unleaded V.S 91/93 premium GAS

There is a very noticeable difference between 87 and 93 with mine - the engine is quieter, smoother, and more power with 93. Prob a +2mpg as well.

The biggest difference is interstate travel in the hills and using cruise control...with 87 it will shift 48 billion times in a half mile going up hill...but the 93 seems to tame that a bit.

 

That's cool that your 91 has no damn Ethanol Shit in it!

 

Others have likely already said this - didn't read entire thread - but I run 87. The engineers that designed the motor built it for that grade, and that's what the manufacturer calls for. I think some people see some differences that they want to see after spending more money for gas at the pump than they have to. But hey, that's just my truck and my opinion!

 

Sure, sure there is.

 

I'm writing this based on my experiences and my opinions.

My driving habits and driving distances are the same every week. With the winter mix out, I do see a significant difference in how long a tank full of 87 compares to a tank full of 93.

My personal opinion is, gas costs money regardless of what it costs per gallon or per grade. I didn't buy my Tacoma to save money on gas. If I spend $40 every two weeks or $50 every two weeks, it doesn't make a difference to me. So, this basically came down to the taco tick. I heard it one day driving in my company's parking garage. It was awful and I had 87 in the tank at the time. Next several fill ups, I used 93 and the tick was significantly reduced, so I've used 93 for months now. 4-5 weeks ago, I filled up with 87 and I barely got 1 week out of the tank. I filled up with 93 a few times ever since that fill up and I average 1.5 weeks per fill up.

Every Tacoma will respond differently based on type of gas, location, weather, tires, etc. Some like and want to us 93 and some will say 87 is fine. It's just like everyone's theory on Cold Air Intakes. It's your money, do what you want to do.

 

So I just bought my truck last week. I was reading the owner's manual and it states that the 4.0L motor can run 87 but it recommends 91+ octane. I'm assuming the VVTi equipped motors are capable of retarding timing to run lower octanes. This would explain the "performance boost" we feel when running higher octanes.

 

I'm sure it's just my imagination.

A-hole

 

I don't mind guys running higher octanes - hey man, it's your truck, you pay for it, you do what you want!

But putting out information for less educated owners that somehow you're going to have engine problems if you run 87 is just silly talk. I'd say most guys run 87, and Tacos are known for their longevity.

 

If memory serves me correct, the first few years of the 4.0 Taco was that way.

 

Stock heads on my motor run 115 - 120.

 

I had a 97 T100 with the 3.4. I always ran mid-grade (usually 87 here in CO). At some point when the truck had 80-100K on it, the check engine light came on. I was running a K&N and my mechanic thought maybe some of the filter oil had messed up a sensor. He cleaned it, light stayed off for 40 miles then back on. Since I'm anal I took it in again but eventually we gave up. It was running great, mileage hadn't changed, so I just go into the habit of ignoring the CEL.

Then one day I was visiting California. It was back when gas was $4/gallon most places, but where I was in CA it was almost 5. So I said screw the mid-grade and filled up with regular. As I drove away from the gas station, the CEL went off. Ran regular from there on out and in another 80K miles it never came back on.

I have been running regular in my Taco. Even though the spec is 87, it runs fine on CO 85. I just did a road trip to the midwest, and on the way back in NE I saw that the 91 was no-ethanol so I filled a tank (a very empty one). The engine kind of seemed more smooth and quiet, but the mileage was no different. Maybe a little worse.

Incidentally, here in CO it's typically 85, 87, or 91. Back when I was pretending to be a college student in Laramie, Wyoming I did a lot of drinking with Petroleum Engineering students. I remember one conversation where a guy told me that, because of the lower density of air in the mountains, lower octane can be roughly equivalent to higher octane. It all comes down to how quickly the vapor burns. As this guy explained, take a cloud of super, and it will burn with a sort of wave. A slow burn makes the expanding gas push more gently but for a longer time (we're talking a difference in microseconds here). So if you have a long stroke, like an old muscle car engine, the high octane pushes the piston through it's whole stroke. Lower octane burns faster. Diesel is way way low, and it just explodes. Take an 87 and burn it in thin air, it's going to be slower. It's also going to be weaker, which is why you get worse mileage at elevation (never mind the hills).

Disclaimer: this knowledge comes from a drunken conversation around a keg 30 years ago. I'd be happy to hear from people who actually know what they are talking about.

 

Best. Disclaimer. Ever.

 

In fact, that's going to my new sig block. Congrats @ColoradoTom !

 

I brought this up a long while ago and nobody was ever anble to explain it. Of love to know why it changed and what the reasoning was but it clearly states in some of the older manuals that higher octane gives better performance.

 

Marc used to have two cylinder sleeves on the 2.5L block. The sub-200hp models had a sleeve with a notch cut in the top of the exhaust port, which lowered compression by allowing some of the fuel/air to bleed out after the intake port was covered. The famous XR6 2.5 used this sleeve. And there 120psi was the norm. But the normal 2.5's at 200hp and 225 were sans the notch and 140-145 was normal, at least on every one I worked on. The Merc racing division took that a bit higher. I ran land and sea dual-plug heads on mine and the compression was above 180psi, and required premium to avoid a melt-down...

 

So something like 36 billion shifts in a half mile vs 48 billion?