toyota tundra, does octane make a difference when towing??

Tundra57

I tow my tab 400 with s 5.7 toyota tundra. Last trip to Florida, i experimented with mid grade (my normal) and the highest octane at the machine. I consistently got 0.5mpg more with the high octane. Never noticed before.

Was this a Fluke?

Dutch061

Using higher than required octane in a vehicle will promote faster carbon buildup. Higher octane burns slower (and cooler) than lower octane.

If, you have higher mileage and/or carbon buildup to the point where there is detonation with 87 octane, the ECU will retard the timing. If this were the case, it is entirely plausible that you could see an increase in MPG using higher octane as the timing would not retard due to detonation. 

Hope this makes sense.

Brad

webers3

I don’t  think you can attribute half a mpg gain to higher octane without taking into consideration all the other factors during your trip ie; changing weather, load, traffic, terrain, etc? You would need a controlled conditions to test your theory, and putting higher octane than your engine requires is a waste of money, and can be harmful to the engine. 

pthomas745

If you were going TO Florida, you were going downhill.  Maybe not much of a downhill run...but downhill. 

TerryHutchinson

Not sure about your Tundra but I suspect the higher octane did help your mpg.  My 3.5 ecoboost Ford F150 runs absolutely fine on regular.  However, it compensates for lower octane fuel by advancing the ignition timing. This, in turn, reduces slightly the power output.  When towing, Ford recommends (does not require) premium fuel for best performance.  AAA tested this a couple years ago and did fine that some high output engines did generate more power and had somewhat better mpg with premium.

DenisP

I only use premium when towing with my Tundra. It is a practice that I have been doing for years beginning  with a Landcruiser with a V8 and continuing with my 2013 Tundra 5.7l. when towing (my boat, Tab or car trailer).  Seems to maximize power and mpg. I have also noticed the Tundra’s towing performance improved after towing for an hour or so after not towing for awhile. I just towed my 400 to Sugarcreek for some work (650miles) and that was my most recent experience. 

TomCanada

My understanding has always been that if your vehicle doesn't require premium, then you won't get any advantage by going to premium.  On the flip side, if it requires premium and you give it something lower-octane, you'll burn more gas and lose power.  I once did a calculation of what saves you more money on a car which requires premium: lower gas mileage + cheaper gas, or higher gas mileage + premium gas.  The results depend on location.  In the USA, the extra cost for premium is low, so it's cheaper to run premium gas since the better mileage more than compensates for the pricier gas.  In Canada, it's different - our premium gas can cost $1 more per gallon (approx $0.25 per liter), so if you're looking to purely save money, you can put regular gas in your premium gas car and you'll save money overall even at reduced gas mileage.

tabiphile

TomCanada said:

My understanding has always been that if your vehicle doesn't require premium, then you won't get any advantage by going to premium. 

You are correct. There is no significant advantage to using anything other than what the engine is designed for. Premium burns hotter but it does not ignite as easily and has less stored energy than the 87 octane that the Tundra is designed to run. The engine control adjusts ignition and (in some vehicles) valve timing optimizing the lower octane performance. Enjoy the fact that your vehicle has been optimized to run the less costly fuel and feed it the cheap stuff. Control your MPG with your foot. What premium fuels add that is less present in lower octanes are fuel cleaners and additives. These do not add power, they simply clean the fuel system. Add a bottle of Techron once in a while and you accomplish the same thing. 
If you are experiencing pre-detonation (pinging) you might then try the higher octane fuel but more likely you should look for a better brand of gas on your next fill-up. Some of the off brand fuels you run into while on a cross country trip may perform poorly. Often mom and pop stations (or even some of the high volume stops) have water in their tanks. If you fill when the tanks are low you can end up with lousy gas in your tank...

TerryHutchinson

https://www.caranddriver.com/features/a28565486/honda-cr-v-vs-bmw-m5-ford-f-150-dodge-charger/

It depends!  If you are driving an F150 with a high output turbocharged engine, it will run fine on regular gas.  But . . . you are not getting all the power out of the vehicle that it is capable of producing on premium.  The engine advances the timing to reduce detonation when running regular. This timing adjustment results in a smooth running engine with a slight reduction in horse power and torque when running regular.

This might matter to you.  It might matter to you even more if you were towing a weight close to the vehicles maximum rating. 

Know your vehicle and how it was designed to operate.  And decide whether regular vs premium is an issue for you and whether or not you are willing to pay more at the pump.

As to keeping your engine clean with fuel additives, as long as you choose a Top Tier gasoline (all the mainstream suppliers such as 76, Shell, BP, ARCO, etc. are Top Tier) then regular as well as premium has the additives.  As an aside - Costco fuel is also a Top Tier gasoline and carries an abundance of detergent additives.

Horigan

tabiphile said:

... If you fill when the tanks are low you can end up with lousy gas in your tank...

I don't believe this is true.  The pumps are at the bottom of the tank.  In fact, you're more likely to get bad gas if the tank has been recently filled, thus stirring up any water or sediment.  Frankly, I wouldn't worry about it.  Just buy top tier gas at the octane recommended for your vehicle.  In general I see turbo engines requiring higher octane.

AirBoss

Wow, that brought back a memory. My father always told me that if you're looking to fill up at a gas station you should avoid the station where the underground tanks are being filled as that sturs up all sorts of sediments which can find there way into your vehicles tank. 

One of those things that I've lived by but can never tell whether or not it was true.

Stick with a Top Tier fuel at the octane recommend and you'll be fine. I do run a bottle of Seafoam thru the system once in while as well. Again...habit. 

GatorEgg

I initially towed our 2018 320 Boondock with my 2003 Tacoma 3.4 Dbcb.  Yes, I picked up about 1-1.5 mpg on premium vice regular while towing.  I upgraded to a 2019 Tacoma with same results.  When headed to the hill country(Smoky Mountains) I now switch over to premium.  I don’t run it all the time, the cost doesn’t balance out to benefit.

Dutch061

tabiphile said:

TomCanada said:

My understanding has always been that if your vehicle doesn't require premium, then you won't get any advantage by going to premium. 

 Premium burns hotter but it does not ignite as easily and has less stored energy than the 87 octane 

I am sorry, this is only partially true. Higher octane burns cooler and produces less "heat" (aka power) than lower octane fuel. Octane is a number assigned to the fuel's resistance to detonation, IE the higher the octane the more resistant to detonation.

The advantage of higher octane is the ability to use higher static compression, more boost, and more timing. Any or all of these increase the power output even though the heat produced is lower per pound of fuel. A great example is race vehicles that use methanol, methanol has a very high octane but it takes 2 times as much fuel to produce the same heat. However, the static compression ratio can be higher, with way more boost on forced induction. 

In the case of electronically controlled systems, this simply allows more boost (if the vehicle has forced induction) or more timing without the detonation sensor detecting pre-ignition (detonation). This alone could potentially explain why the original poster saw a .5 MPG increase in mileage.

I have a 2017 F-150 with a 3.5 Ecoboost with a tuner installed. For the performance tow tune that I run, you MUST run premium or it doesn't run as well.

Brad

Tundra57

Wow a lot of comments. Some agree some dont. Ill have to try it a few more times for consistency, but im pretty sure its better with premium when towing. I use mid grade normally. Thanks for the lively discussion.

The only thing I disagree with is that higher octane fuel will damage or soot up the engine. The only difference is maybe some additives and an octane booster. The fuel is the same. So I dont see why it would cause any problems. If it did, Toyota would advise against using high octane fuel.

Dutch061

@Tundra57 the reason it can increase carbon build up is because it burns slower and with less heat. This can promote the rate at which combustion chamber deposits and carbon builds up on the back sides of the valves. It will not mechanically damage the engine, unless there was so much carbon build up that it started to break off and fall into the combustion chambers.  

I am speaking from dozens of years as a Master Automotive Technician and can say that the words I have spoken will align with ANY vehicle manufacturer. 

Brad

Tundra57

@Dutch061 thanks. Makes sense. Since i only have tried the higher octane for towing and most of my miles are normal around town with mid grade, then I think I am safe lol.

Dutch061

@Tundra57 you will be absolutely fine, no worries.

Brad

DenisP

I checked my 2013 Tundra owners manual. As stated, using higher octane is appropriate. I will continue to use premium while towing as long as funds allow. 

tabiphile

Since your 2013 has Iridium plugs you should not need to worry about changing them until North of 100,000 miles. Otherwise can have a major affect on MPG and especially as they near the end of their service life. They will have a much greater impact on MPG (if they are worn) then you will be able to reliably measure by changing fuel. The 4.7 motor has plugs that need to be changed at 60,000 miles as do the 6 cylinder Tacomas. 

DenisP

@tabiphile thanks for the spark plug reminder. After reading your post, I ordered and installed new plugs on my Tundra. At 113k the plugs looked good but it was time for a change. First impression is smooth power and the real test is driving 650 miles to Sugarcreek to pick up my 400 after service to check if there is any improvement in MPG.