You shouldn't use 86 or 85 grade gas, right?

My wife put 87 octane in my Macan and it was not happy. The engine made a weird growling sound and it refused to engage sport mode, but never threw a check engine code. That’s with the golf 2 L engine. Just because the engine is taking heroic measures to prevent from being damaged doesn’t mean it’s something you should be doing.

 

That’s why I said:

 

i got really worried here for a minute that my fuel costs were going to jump up significantly...

then i remembered i live in Canada and our lowest octane fuel is 87 anyways.

 

Gasoline is like refrigerators.

This one keeps your good cold for $500, that one keeps your food cold for $4000.

This one makes your car go for $2.50/gal, that one makes your car go for $3.50 per gallon.

Onus is on the gas enthusiasts to show the data from a real scientific study that shows you’re more likely than not to blow your engine with the wrong octane. Most drivers don’t push their engine hard enough to get all the power anyway so I don’t care about “power loss” arguments. Otherwise, SCOREBOARD!

 

I’m driving alI I-40 across NM and TX - And I can’t find 87. I have been putting in 88. Since it is not rec to use anything lower - But damn, I leave Commiefornia’s $5 gas prices eager to get below $3 and still can’t do it. $2.67 for 86. $3.14 for 88.

 

Isn’t 87 or higher in the manual.

 

A modern fuel injected forced induction engine can handle a grade lower octane fuel and be fine. It will pull timing and play tricks to prevent precombustion but it won’t cause damage. I don’t know why you wouldn’t spend the extra $10 to keep the full engine performance but hitting the wrong selection occasionally won’t hurt anything.

 

Yeah, this is what I have always wanted to see some real-world data on. Maybe we can get the Project Farm dude to do a comparison or something. I've always thought, yeah, you can use 87, but the adjustments the engine does reduces performance.

What I want to see is what adjustments the vehicle is doing, if any, with 87 octane compared to what it does with 91 or 93. And if it's different, what that may mean in terms of output, efficiency, and longevity (those might be harder to prove with real data).

In the end, though, I have serious doubts as to whether the difference in performance/efficiency would make up for the difference in cost, at least in the short term. Long-term, it's really hard to ever know.

EDIT: Oh, and I've used 85 and 86 in mountainous areas where that is all that is available. It works fine, at least at higher altitudes.

 

The high elevation exception is for carbureted cars vs fuel injected, not N/A vs F/I.

 

People will spend $10+ for a quart of boutique oils, use expensive after market oil filters, halve the oil change interval, buy fancy tires, and yet cheap out on the one essential fluid that gets used more in a vehicle than any other: the fuel.

 

Testing on our newly acquired development 2024 Tacoma has shown some pretty shocking results in the difference between 85 Octane and 91 Octane (here in Utah). Same truck. Same dyno, 1 week apart.

 

What are the different color plot lines?

 

Amended the image above.

 

Yay, some real data, thanks for posting this! I'm assuming other variables like ambient temp were similar. That's a 7.5% increase in HP and a 13% increase in torque. More than I thought there might be (and debunks the theory that it doesn't matter at all). It doesn't quite seem to make up the difference in cost for those who only care about that, but it does show that there is a difference. Probably matters more on the 2024 with the turbo.

 

I wonder what mode the dyno truck was in for the testing?

 

85 Octane (Red) was done in: 85.10degF, 25.93in-hg, Humidity: 27.55% for an SAE Correction of 1.18
91 Octane (Blue) was done in 72.50degF, 25.58in-hg, Humidity: 38.08% for an SAE Correction of 1.18

 

Normal - for these specific tests.

I don't think we'll see any difference in actual peak output between the modes, but we'll be conducting testing to validate that.

 

this is actually a lot more interesting big picture. No one's done any videos on this for this engine, despite its widespread adoption by Toyota. You guys could put together a cool YouTube video. Even if it's just the discussion of the results and the implications.

It's really eye-opening to see the difference in octane and output even on stock. You'll always hear people that say hey I run 85 octane at altitude. Yeah well I have too in an 11:1 compression engine that's naturally aspirated. But a turbo is not the same.

 

Very interesting idea. While a bit off-topic from the title here, we do plan to get pretty data-intensive on this platform and the new Tundra. Let's say preliminary tests with 'tuned' calibrations have shown compelling improvements in output over any previous N/A calibrations we've offered. The need for proper data collection with testing and proofing with this platform should be paramount. Thermal management is going to be important on these platforms.

 

Honestly, I think you should follow the manufacturers' recommendations and run 87 or better. It's true that modern engines have much better knock detection and mitigation strategies than those of yesteryear and you might be able to get away with it more readily. The AKI rating of fuel is a minimum. What comes out of the nozzle when you select 87 is at least 87. If you pick 86, you'll be getting anything from 86 on up. Sure, the refinery is going to work to keep the rated AKI close to the actual AKI as to not waste money and the station won't give you higher rated stuff unless it has to. You're probably not getting better gas for cheaper very often. But, do you really want to lean on that? The software's probably pretty good and probably will pull timing to deal with it. Except when it isnt: https://www.vwvortex.com/threads/never-fill-a-cadillac-srx-turbo-with-regular-unleaded-gas.4819694/ Admittedly, that was a long time ago and it was a fluke, but it can happen. You're only saving, what, a couple bucks per tank at most? If that's important, what else are you skimping on when you bought an expensive vehicle? Just use the correct stuff.