I am looking into buying a GX 460 soon. Have any of you been running regular gas. I have been running regular gas on my 03 V8 4runner since new with no problems but not sure about the new 4.6. I really just want to run regular.

The GX460 has been designed and tuned to require premium fuel.

Koz

The 4.6 is in other vehicles that don't require premium, what would Lexus do that makes it require premium. I asked a Lexus salesperson and he didn't really have an answer (as expected) when i pointed out it was in all kinds of Toyotas.

Despite the engines being very similar, you can see there are some tell-tale signs that they are very different.

If you'll look here at the 2012 gx460 specs http://pressroom.toyota.com/releases...+info.download

and here at the 2012 tundra specs http://pressroom.toyota.com/releases...tures.download
you'll see that they do in fact both have the "same" 4.6 liters of engine. The differences start to pile up immediately though. For instance, in the tundra the bore and stoke is: 3.70 x 3.30 in. In the GX460, it is 3.70 in. x 3.27 in.

GX460 hp numbers: Horsepower (SAE) 301 hp @ 5,500 rpm
Torque 329 lb.-ft. @ 3,500 rpm

Tundra hp numbers: Horsepower 310 hp @ 5,600 rpm,
Torque 327 lb-ft @ 3,400 rpm

Also, we see that the tundra engine is Direct injection alone, wheras the GX460 version is MFI.

So despite both engine being of the same designation, the gx460 requires 91 unleaded because it was designed for it obviously. It's quite possible that the gx460 ecu is programmed more aggressively to take advantage of the higher octane and the tundra is not.

Take your pick of reasons that they differ, the point is if the manufacturer recommends premium it is because the engine was designed to and runs "better" on it than on regular, whereas that might be the exact opposite for the tundra.

I was in a similar situation before we purchased our GX470 coming from a 5.3l envoy. All in all we spend about 4-6 dollars more a tank and get the same or better mileage so I really wouldnt be that concerned about just buying the premium. Also, it probably wouldnt help to put regular in it anyway, because the ecu will probably detune the the engine accordingly to knock it may sense. You wouldnt know that its happened until after you got worse mileage....

I have owned a gx470 for 5 years and have run both 87 and 93 at diff times. The 93 gets better mileage by 2 miles to the gallon (20mpg compared to 18 with 87 octane- highway mileage.) I have never heard it ping or knock with the lower octane. The shop that works on my truck says it will run fine on 87 or 93. The owners manual says nothing less than 87 but suggests 91 for better performance

The 4.7 was designed to run on regular. Unless you towed close to the maximum tow rating there was/is no benefit to running premium fuel. The ONLY purpose for running higher octane fuel is to prevent engine knock/ping. There is no difference in the amount of energy between regular and premium fuel. The best fuel to use is the lowest octane fuel that will not cause knock (usually OEM recommended octane). Using higher octane (on a stock engine) then what the OEM recommends is a waste of money!

When an older engine has carbon build-up (raising the compression ratio) that can not be removed (or you do not want to spend the money to clean), you can use a higher octane to prevent knock.

Koz

BTW - The reason the GX requires premium fuel is because the GX's 1UR-FR 4.6 engine is tuned (valve timing) to be smoother and quieter.

Koz

Toyota recommends 87 or higher or premium for "improved vehicle performance" in the 4th gen.

I tested the 4.7 V8 with regular and premium and there was NO difference in milage (even when towing). What is more important then octane is how well your fuel keeps your engine clean.

Top Tier Gasoline

Koz

Who knows, but use of premium does qualify as an OEM recommendation.

I'd rather have the 9hp and run on regular!

Koz

The new 4.6 in the Tundra is not direct injected. They are both still MFI.


Here is what I know about the new 4.6L. It makes more power than the outgoing 4.7L. It's a chain motor as opposed to the old 4.7L (no more timing belt maintenance). It has dual VVT-i like the 5.7L and built very similarly architecture compared to the 5.7L.

If it's built in Japan, it will probably use premium gas. My 2001 LC has the same engine as a Sequoia/Tundra, 2UZ. The Lexus LX 470 of the same year is also made in Japan.

The reason being is minimum Octane in the rest of the world is 93, where as in North America it's "watered" down to 87. I guess they (Toyota Engineers) are too lazy to tweek the ECU to take the lower grade fuel.

The GX460 as opposed to the Tundra/Sequoia has a full time center differential that is always working that according to proper SAE specs will reduce HP/TQ ratings versus the Tundra/Sequoia 4.6. So to compensate any HP/TQ robbed by the center diff always working would need and require premium fuel. The 4Runner also has the a part time and full time system in their line up both models are not tested.

Land Cruiser 200 4.6 is set up exactly the same as the Tundra 4.6 however the ratings are 304/310tq and 324/327tq

There has to be an error somewhere by Toyota that nobody has caught yet. The Lexus GX in Canada is listed at 329 lb.-ft. @ 3,400 rpm whereas the GX is listed at 329 lb.-ft. @ 3,500 rpm. Worldwide rating for the Land Cruiser 200 4.6 use the 3,400 rpm listing.