Highlander Gas Mileage, Tips & Octane

[Brklyndriver]

Since the prices fell I changed to premium at the mechanics advice that I shouldn't use regular unless i have to. Haven't really bothered to check the mpg now and not noticing much difference performance wise. But it is definitly a good observation u made.

[edwardh1]

what about tire pressure - say 30 vs 34

what are you guys using?

[Ricola]

I still don't think there is an economic advantage to using premium. I think we are paying 25 to 30 cents difference between 87 and 92 octane. You are probably only going to get 1 or 2 miles per gallon improvement. Paying an extra 5 or 6 dollars for 19 to 38 miles per tank doesn't make sense. Also, you can get 1 or 2 mpg improvement by just making easier stops and starts, and lowing your speed a little.

[Brklyndriver]

Originally Posted by Ricola

I still don't think there is an economic advantage to using premium. I think we are paying 25 to 30 cents difference between 87 and 92 octane. You are probably only going to get 1 or 2 miles per gallon improvement. Paying an extra 5 or 6 dollars for 19 to 38 miles per tank doesn't make sense. Also, you can get 1 or 2 mpg improvement by just making easier stops and starts, and lowing your speed a little.

Premium is better for your engine and most people say it does improve performance so even if your calculations are correct there are other advantages to it making it worth it.

[Ricola]

How is it better for your engine? Engines have sensors that adjust to compensate for a difference in octane. If it runs fine and does not knock, there is no difference and no harm to the engine. Getting more horsepower from a fuel doesn't make it better for your engine, if that were true, then going to nitro or alcohol would be even better for the engine.
Now if the difference between 87 and 92 octane where .02 cents, then the higher octane would be a better buy.

[Brklyndriver]

its better because 87 octane doesn't fully burn in your engine and leaves residue.

[Ricola]

Sorry, but I still disagree. Lower octanes are known for causing pre-ignition or knocking. Lower octanes burn at lower temperatures. Higher octanes burn at higher temperatures and thus less chance to pre-ignite. If any gas was going to leave a residue it would be a higher octane in a car that does not need it. There has been a concern for higher octanes leaving unburned gas in the emisson control systems.
Excess deposits on valves are also know to cause pre-ignition. The deposits soak up some of the fuel and cause pre-ignition. Usually in older cars. A high octane can remedy this due to its high temperature require to burn.

Here is a quote for CanadianDriver.com:

"Many drivers believe that using a premium grade fuel is better for their vehicle and produces more power. Not true. As long as the fuel does not pre-ignite, any grade of fuel will produce the same amount of power. Save some money at the pumps and optimize your fuel economy by selecting the correct grade of fuel for your operating requirements."

[v8Toilet]

The only difference between 87, 89, 91, and 93 is the flash point of the fuel. It’s false to say one cleans better than the other or that one will gum up your engine. That is what the fuel companies want you to believe so you buy the higher octane fuels.

The flash point is the point at which the fuel self ignites under high temperatures. The higher the flash point the higher the temperature the fuel can withstand before it self ignites. In the engine you want the spark plug to ignite the fuel not for it to ignite by itself. As the engine compresses the air fuel mixture the air fuel mixture gets hot because it is under pressure. Higher compression engines that compress the air fuel mixture more require a higher octane fuel because compressing the air fuel mixture more produces more heat buildup.

Some cars like yours have knock sensors that sense the fuel self igniting (known as pre ignition) and change spark ignition timing to help reduce those temperatures. This is especially helpful because sometimes right after the spark plug ignites the fuel the flame front traveling across the cylinder raises the temperatures enough before it consumes all the fuel so that another flame front starts before all the fuel is consumed. This is known as detonation. When your computer reduces spark ignition timing because it sensed detonation the reduced spark timing reduces the engines power and fuel economy as a side effect. So only with engines that need it like high compression engines will you need to use higher octane fuels because otherwise you are getting no benefit from them like the fuel companies would like you to believe. Most cars today with high compression engines will run on 87 or 93 because of these electronic gizmos called knock sensors but they will make more power and get slightly better fuel economy with the higher octane because the computer can give the engine more ignition spark advance.

[Void]

Top Shelf explanation. Thanks.

[alkazoo]

hiya highlander forum!
Im the new owner of a slightly used 2003 highlander, V6.
Bought it with 22k on it, one owner, non smoker, looks/feels/smells/rides like brand new.
Im not quite happy yet with the mpg im getting. In the 600 miles ive put on it since owning, ive only averaged approx 16 mpg highway. I was expecting a little better anyway ( 18 to 22 ??). I noticed the last place that changed the oil put 10w30 in it, Owners manual and engine filler cap all insist on 5w30..will correct wieght oil help mpg? Any other tips? I have a tank of higher octane gas in it now and will check mileage at next fillup...Other then that would appreciate any tips etc? thankyou

[breugel]

I have found the following...
93 Octane helps with millage and it has much more pep.
Be easy on the throttle. This helps a lot on City driving
speed >70 kills the milage

On a recent trip 250 mile (highway and rural road with about 6 small towns)with 93 octane I got 25 MPG
On the rural roads @ 55 I was getting about 27 mpg and on the interstate @ 70 I was getting about 23 mpg.

Drop it all by about 2 mpg for regular.

I have a 3.3L V6

[05MNTH]

Check your tire pressure!!

Air filter been replaced lately?

The premium fuel WILL help economy (maybe 2mpg?) but the cost typically outwieghs the benefits. Do the math.

Correct weight (in this case lighter weight) oil will help buy putting in a good synthetic (Mobil 1 for my money) will certainly garner a 1-2 mpg gain.

[v8Toilet]

The lighter weight will help your gas mileage but it won't be 2 mpg. It will help the oil reach the engine parts quicker though upon startup so switching back to 5w-30w is a good idea.

The correct tire pressure though in conjunction with a clean air filter will greatly help gas mileage.

[drewdog]

Originally Posted by breugel

I have found the following...
93 Octane helps with millage and it has much more pep.
Be easy on the throttle. This helps a lot on City driving
speed >70 kills the milage

On a recent trip 250 mile (highway and rural road with about 6 small towns)with 93 octane I got 25 MPG
On the rural roads @ 55 I was getting about 27 mpg and on the interstate @ 70 I was getting about 23 mpg.

Drop it all by about 2 mpg for regular.

I have a 3.3L V6

wow. i have a '02 V6 AWD limited and i got best 22 MPG on last trip. I use midgrade fuel, but i do admit i ave. at least 65 mph.....

[kedruff]

I've got an '04 4cyl AWD w/ 15k miles on it. When I first bought it "new" with 7k miles on it (the dealer is a friend and his wife had been driving it, so it wasn't titled), I got 23 mpg on the interstate (had a/c running, etc.) I averaged about 80 mph and I was driving west across Tenneessee on I-40. West on I-40 is MOSTLY downhill.

On the way back to Virginia in December, I drove east across TN on I-40 and averaged probably 85 mph or so driving mostly UP hill. I got less than 20 mpg. I didn't measure it on the way back. I am going to try putting premium in it the next time I fill up to see if I feel more pep and/or get better mpg.

KD