Fuel for Gx460? Regular or hi-octane

[Sultan]

I have a 2022 GX460.

other than performance, what pro/cons are there between premium vs regular fuel?

is either more economical on consumption?

any long term benefits of hi-octane?

 

[RX400h]

The key is in the owner's manual wording. Is 91 octane fuel recommended or required? If it is required, you should not use anything else. If a safeguard like a knock sensor malfunctions, the result could be engine damage. Costco has good fuel prices for premium. That's what I use in two of my cars that require that grade.

[Kike_GX460]

I recently purchase a GX 2019 with 36k miles on it, I also use costco fuel, is working out ok. I’m averaging 17.8 per gallon suburban City driving. Always on eco mode and shifting to S mode if high rise bridge or road.

[dcfish]

I burn only the highest octane that is available, Usually 91 here. I never use anything else, Nor would I...Not even in my lawn mower  😉

[EMGX460]

Octane is not well understood. Octane rating measures the fuel’s volatility or resistance to premature detonation, not the energy content in the fuel.

Higher compression engines are more likely to experience fuel explosion prior to spark plug firing than lower compression engines. Diesel engines don’t have spark plugs because they rely on high compression to compress the fuel to the point of detonation of the fuel-air mixture.

Modern engines have knock sensors to detect early detonation and adjust timing and fuel-air mixture to reduce early fuel explosion.

Knocking robs you of power because the engine is working against itself. If it is bad enough, it can result in engine damage or even destruction.

But there are other ways to prevent premature detonation of the fuel rather than burning “premium” or high octane fuel.

Part of the reason high compression engines tend to experience early detonation of fuel is the higher compression results in increased heat, and if there are any combustion by-products like carbon on the top of the piston, bottom of the head, valve surface, etc. they can create “hot spots” which can ignite fuel prior to spark plug firing.

A fuel additive like Schaeffer’s Soy Ultra that cleans deposits and increases the lubricity of the fuel up to 40% can at the same time reduce the volatility of the fuel. Treat cost is less than 6 cents per gallon (1 gallon treats 2,000 gallons of fuel) so much cheaper than burning premium high octane fuel.

In addition to cleaning up the fuel system and removing / preventing deposits it stabilizes the fuel, prevents varnish, etc.

I started running it 18 months ago in all my gasoline ICE powered equipment. Previously I had been running premium no-ethanol fuel (pure gas) which was both expensive and inconvenient due to only a small percentage of stations offering it.

I have had no problems with carburetors on seldom-used equipment like air compressors, pressure washers, 3-pt tractor sprayers, etc. No problems with 4-wheelers, truck, car SUV. In my 2017 Ford F350 with 6.2 liter V8 port injected engine I saw marked improvement in fuel economy. I get about 80 more miles per fill-up than I had previously and I track all my fuel consumption with Fuelly app.

Octane won’t always fix it either. Your oil can make a difference. The trend toward smaller displacement, direct injected, turbo-charged engines created carbon problems and in particular low speed pre-ignition (LSPI) or “super-knock” or “mega-knock” which was intermittent and could actually destroy an engine the first time it happened or not destroy it for many times.

After a lot of research on the cause, it was determined that the presence of calcium additive (an oil detergent additive) in the engine oil was reacting with combustion by-products specifically on these small-displacement, direct-injected engines and causing severe premature detonation of fuel under certain conditions.

Oil manufactures created a new oil that replaced most of the calcium with magnesium for detergent to combat LSPI. These oils carry the API SN Plus or SP symbol and rating.

All of this said to say that buying premium fuel is the most universal method of controlling pre-ignition of fuel because premium fuel while containing the same energy (BTU) per gallon is less volatile, less likely to explode prior to plug firing just due to compression or heat.

But it is not the best way to prevent pre-ignition / labor knock / engine / fuel system damage and it certainly is not the lowest cost.

Use a good quality gasoline fuel additive like Schaeffer’s Soy Ultra that improves the fuel stability, lubricity, cleans and lubricates injectors and fuel pumps, and improves fuel economy to boot. Premium is just the easy way because virtually every station offers premium and it makes more money for the station, wholesalers, and oil companies.

Premium fuel has roughly the same production cost as regular so profit margins on premium high octane fuel typically exceed double the margin earned on regular octane. Remember it isn’t a different fuel, it is just a fuel with an additive package to reduce the volatility of the fuel which is measured in octane rating.

A final point to consider is that when you read the manufacture recommendations for oil viscosity or fuel on the same exact vehicle, same engine, but in a different country they often vary. For example in a country like Russia where the usage or climate (or both) is more extreme you often see manufacturers (who want their vehicles to make it past warranty period before failing) recommending a step thicker viscosity. For example rather than 0W-20 they might recommend 5W-30.

They recommend the thinner oil in the United States because our government has mandated specific “fleet” fuel economy for automobile manufacturers. So the manufacturers are doing everything they can to improve fuel economy. Thicker oil causes more drag on lubricated parts which requires more energy to turn the same RPMs or produce the same horsepower or torque. Thinning the oil is an easy way (and free to the manufacturers) to improve fuel economy slightly across the fleet.

This is also why we are seeing large displacement normally aspirated V-8 engines disappear and a trend toward 6-cylinder or 4-cylinder small displacement turbocharged engines. It is why we are seeing aluminum bodies, thinner metal that dents easier, plastic replacing metal, thinner seats, smaller sizes, lighter tires, etc. It is why some vehicles have been discontinued altogether. All of it is chasing the CAFE standards for targeted fleet MPG where all cars produced by a manufacture must meet specific MPG standards or they are fined large fines.

It is why vehicles have gone up in price so much. High-pressure common-rail, direct injection inside the cylinder is far more complex than low-pressure multi-port fuel injection in the intake manifold. It is less dependable long-term due to the contaminants, temperatures, and pressures the injectors are exposed to. The high heat and small injector spray opening size makes injectors more susceptible to failing due to water in the fuel (causing steam flash which can blow the tip of injector off due to rapid expansion).

The air-fuel mixture can be more precise and you can get more power from smaller displacement and less fuel resulting in better fuel economy. But it all comes at a price. The complexity of the design is inherently less dependable and does not last as long.

The premium and regular and mid octane fuels have been around for many years prior to the change to direct injection. So the premium fuel does little to battle carbon buildup that plagues the direct-injected engines.

Years ago I had a 2008 Lexus IS-250 AWD which was one of the earliest direct injected engines eat itself due to carbon buildup on the intake valves. At the time the car had less than 80,000 miles on it and the issue was not yet prevalent as the engines were just reaching the age where they were starting to fail.

That is why I drive a Lexus GX-460 with a normally aspirated 4.6 liter V-8 engine that utilizes multi-port injection rather than direct injection. It is why I drive a Ford F350 with normally aspirated 6.2 liter V-8 engine that utilizes multi-port fuel injection.

Neither get as good of gas mileage as the more modern engine options that utilize complex direct-injection. But a $10,000 engine failure at 80,000 miles costs a lot more than the difference in operating cost to lower MPG.

But while premium fuel is recommended in USA and it will help reduce (but not necessarily eliminate) knock due to pre-ignition, it does little to address carbon or fuel system failure due to lack of lubrication (lead in older gas was a great lubricant just like sulfur in old diesel was). 

So for my money, I run a good quality fuel additive and burn the low octane fuel but treated.

[dcfish]

Fuel additives play hell on Catalytic Converters and Sensors...Been there...Just Burn Premium no ethanol Period. 

[EMGX460]

That statement that additives play havoc on sensors and emission components etc. would depend on the additives. The difference in regular and premium is in fact mostly additional additives.

Additives that can damage fuel systems either contain high concentration of ethanol or alcohol (which are fine for flex fuel vehicles but can damage non-flex-fuel vehicles) or additives that utilize organometallic additives.

Organometallic additives are chemical compounds that contain at least one bond between a carbon atom and a metal or metalloid. You would see names like n-butyl lithium (n-BuLi) or diethylzinc (Et2Zn) or tributyltin hydride (Bu3SnH) or triethylborane (Et3B), etc. Lexus owners manual specifically warns against use of an octane improving additive called MMT (Methylcy clopenta-dienyl Manganese Tricarbonyl) which is a manganese based additive (again a metal) but only .02% of all gasoline sold in America uses this additive, and at levels that are considered safe for emissions systems.

The Schaeffer’s Soy Ultra I mentioned contains no ethanol (but it is formulated for use in Ethanol-containing fuels including 87, 91, E85, etc.) It also does not contain organometallic additives. It actually is formulated using similar aromatic petroleum hydrocarbons as the gasoline manufacturers use in creating premium fuel. Lexus actually recommends using “Top Tier” fuels which are fuels that contain additional additives including additional detergents, but does not contain organometallic additives. So additives themselves are not the problem since “Top Fuel” stations carry gas that typically had additional additives and in particular detergents.

While there are multiple methods of increasing the octane rating of gasoline, refineries typically use aromatics like toluene, branched alkanes, or even ethanol to increase the octane. Higher octane race fuel may be made by modifying the molecules through cracking the molecules etc.

Piston aircraft fuel (known as 100 low lead) still uses lead as an additive to increase octane. Lead also increased the lubricity of gasoline fuel, just as sulfur increased the lubricity of diesel fuel before low sulfur diesel fuel was mandated. All premium fuel at one time used lead as an additive, but lead was removed from automotive fuel due to it being toxic.

Today, typical automotive gas premium fuels use additives and also commonly contain additional detergent additives to help keep the fuel systems cleaner. These are some of the same additives used in high quality fuel treatments.

Some fuel additives (like Schaeffer’s products) are actually blended into the fuel you buy at fuel stations. In fact you can go onto the Schaeffer’s website and find stations that use Schaeffer’s additives in their diesel fuel.

But you don’t reduce volatility in gasoline (increase octane) without the addition of additives, it isn’t a different fuel, it is the same fuel with an additive blended into the fuel.

So you can’t say that additives in general cause problems because if that was the case then premium fuels would also cause problems.

Buying premium at the pump is just the convenient way of getting the additives that increase octane by lowering volatility of the fuel and reducing the likelihood of premature detonation. You pay for the convenience and as mentioned the margin per gallon on premium fuels is much higher than regular.

There is the same amount of energy per gallon in both regular and premium. The difference is whether the fuel detonates before the spark and causes the engine to work against itself which is more likely in high performance, high compression engines, or engines that run hotter or at high RPM. But if you buy a good quality fuel additive that increases lubricity and detergents it will reduce the volatility of the fuel.

The octane rating of pure 100% ethanol is 100 octane. When mixed with gasoline, ethanol performs as if it’s octane rating is 112. So ethanol is an effective way to increase the octane rating of gasoline. E85 fuel that can be burned by “flex fuel” vehicles has an octane rating of 100 to 105. But due to the high alcohol content it can damage fuel system components unless they are made to burn high ethanol content fuel. E85 will also make it hard to start your vehicle in very cold temperatures as it is nearly impossible to vaporize the fuel. It can also attract water and cause corrosion.

But it isn’t true that all fuel additives will damage fuel systems, sensors, etc. Some may, especially cheap ones. But the better additives help keep your fuel free from accumulated water, clean injectors, increase lubricity of fuel which reduces wear, and can reduce the volatility of fuel which the combination of clean injectors more efficiently vaporizing the fuel and lower volatility reducing early detonation can increase fuel economy.

Higher octane in and of itself won’t increase fuel economy. Flex fuel vehicles get worse fuel economy running E85 (which is 100 to 105 octane) than they do running 87 octane regular gasoline.

But a high quality fuel additive like Schaeffer’s Soy Ultra basically contains similar if not identical additives that are used in producing premium high octane fuels, it just costs less to treat regular gasoline than it does to buy premium which is pre-treated with similar additives.

They same is true of diesel fuel. When farmers buy bulk fuel they typically have the option of buying fuel pre-treated with additional additives to increase lubricity, help eliminate water, reduce or eliminate algae, and increase the cetane of diesel fuel.

It isn’t a question of using additives, because that is generally what the difference is between “regular” and “premium” fuel whether gasoline or diesel. It is what chemicals do the additives use to boost the octane rating (or cetane for diesel fuel)?

There is a big difference between 6 cents per gallon treat cost and the national average 83 cents per gallon difference in regular and premium fuel.

I personally think I get an even better quality of fuel by treating regular with Soy Ultra, and for far less cost per gallon than buying premium.

I also know I have seen a marked improvement in fuel economy from all vehicles, but especially my 6.2 liter Ford V8 in my F350.. I am getting more than 50 additional miles per fill-up on average. More than a 1 MPG improvement.

I also get better fuel economy with my GX460 and I am averaging more than the EPA says I will get by about 1 MPG.

I know that my Honda-powered air compressor, tractor mounted sprayer, power washer, or my Kubota gasoline engine on my ZG327, and all my Stihl gasoline power equipment starts and runs better than it did when I was buying premium “pure fuel” which was zero ethanol. I have not had one problem with a carburetor since switching from pure gas to regular treated with Soy Ultra.

I have had no carburator replacements, faster and easier starting, smother running, and improved MPG. That is true of both frequently used and infrequently used engines.

There may be other quality fuel treatments that would do the same, but I have tried stabil, sea foam, and others with no obvious difference in starting, power, or fuel consumption.

So I am sticking to the Soy Ultra for gas and CarbonTreat for diesel because I have personally experienced good results.

But that is just me. To each his (or her) own. As the saying goes, ‘your mileage may vary.’

 

[Crackerjack1923]

Schaeffer Manufacturing Co. 0131C-021S SoyUltra Gasoline Additive, 12 oz. Bottle sells for $20.00 on Amazon, and instructions say to add an entire bottle to each tank of gas!!!  That would add $1.00 per gallon to the price of a tank of gas! Unless I've missed something, no thank you!  It is cheaper and more convenient, obviously to just fill up with premium.  Have I misunderstood something?