Regular Unleaded or Premium Unleaded?

[2000TLC]

Does anyone have an opinion or factual info about running regular unleaded in your 100 series? Is it actually going to hurt the vehicle in the long run? I know the owner's manual says to use Premium, but as we all know Premium gas costs an ass load. I know, your thinking, if I am worried about fuel cost then why did I buy a Land Cruiser. The cost is not that big of a deal. I honestly do not think it really matters. Unless, I was running regular unleaded constantly and then I am sure it would cause problems later on down the road. I have been using regular unleaded on every other tank of gas and my TLC has been running fine. No knock or ping. What do you guys think?

[macneill]

I alternate tanks too, and once in a while, I'll go for the middle grade.

[DMX84]

Your ECU will learn all the bad habits of you driving, including your bad gas. It won’t “hurt” it to run low octane gas IMAO. However it will suffer performance over a long period of time. If you switch back and forth form low & high octane gas you will prolong the effect of the gradual diminish of the performance. Your ECU is making/seeing adjustment for timing, knock, barometric pressure, and low, med & high fuel trims etc.etc. Unfortunately the bad gas is one thing that is not reset every time you start your car and it may take several tanks to bring the timing backup to the proper performance of what its designed to run at with premium gas.
Dean

[macneill]

Originally Posted by DMX84

Your ECU will learn all the bad habits of you driving, including your bad gas. It won’t “hurt” it to run low octane gas IMAO. However it will suffer performance over a long period of time. If you switch back and forth form low & high octane gas you will prolong the effect of the gradual diminish of the performance. Your ECU is making/seeing adjustment for timing, knock, barometric pressure, and low, med & high fuel trims etc.etc. Unfortunately the bad gas is one thing that is not reset every time you start your car and it may take several tanks to bring the timing backup to the proper performance of what its designed to run at with premium gas.
Dean

Did not know that. Better stick with the good stuff. Thanks.

[jjbodean1970]

i run mid-grade every tank based on the opinion of people who work for the factory

[DMX84]

Originally Posted by macneill

Did not know that. Better stick with the good stuff. Thanks.

But for what it worth is it really necessary to run premium all the time? I don’t think so, I run regular unleaded in mine. (It’s not the fastest accelerating car I’ve driven nor is it intended to be, but, @ ~110mph the LC lacked power.) Who knows what the PO was running in it, could have been half & half. IMO just run regular, and before the trip to Moab or whatever, disconnect the battery to reset the ECU. (I’m not positive this will work on this ECU, but I think so.) Then run premium on the whole trip for best performance/economy. I plan on looking more into this subject soon. I’ll keep everyone posted on my findings with the logger to find out how much knock is detected & monitor how much timing is being pulled etc.
Dean

[dnp]

I didn't know that about the ecu's "memory" either, but I have noticed a marked difference in performance when I run regular. Mine seems to respond immediatly to octane changes, but it may be that I'm not experiencing the total benefit until some time after the changeover. I usually do it this way: If I'm going on a trip and will be cruising at a steady speed for many miles, I'll run regular. Otherwise, for city driving, I prefer the extra "feel" of premium

[NMuzj100]

I think that there is no possible damage that could come of running regular (so long as you don't get knocking or pinging - and that is not likely) but it will be impossible to get the maximum performance from the engine. The ECU will adjust to allow the best operation for conditions.

The "Premium Fuel Only" sticker is there to keep people from putting in low test gas and then complaining that their crusier doesn't make the promised power. Wish I had a 4wd dyno to measure actual peak power lost when running lower octane/compression levels ( my guess is small loss).

Engine gurus - Will this loss theoretically be throughout the power/torque curve or only at the higher levels ?

My $.02 ( uninformed) - The ECU might adjust very quickly to the lower or higher octane level just as it does temp/air density ect...( in fact I doubt it measures octane independently [no octane sensor] but calculates it from other known variables) The only area that it probably takes time to adjust to is to driver imputs so that a temporary wild streak or driver change doesn't rapidly alter the vehicle's "feel" to the driver.

[e9999]

our 03 owner's manual states that 87 is OK but higher octane will give better performance

[DMX84]

It’s not an “octane sensor”. It uses the knock sensor to detect knocking & its not necessarily audible. If you do hear knock than you have a much more serious condition.
Here is some good information on this subject.
The "octane value" is a term coined by Todd Day to refer to the memory address that is used as a longterm timing trim. If the ECU hears a moderate amount of knock for a long time, or alot of knock for a shorter amount of time, it will keep reducing the value in this memory address. Normally set at 255 (FULL), it will keep getting reduced as long as it hears knock. This could be due to just getting a bad tank of gas, or perhaps running more boost than you are tuned for. But, even if you fix the problem, by filling back up with good premium fuel, or turning down the boost, the "octane value" can take several hundred miles to work its way back up to "FULL" value again.
Dean

[jjbodean1970]

Originally Posted by e9999

our 03 owner's manual states that 87 is OK but higher octane will give better performance

premium was only recommended for the 1998 to 2000 models, 2001 and up regular is the recommended fuel according to the factory

[hank14]

The PO had been using regular unleaded in my 99 for over a year when I bought it in 2003. It had 116,000 miles on it. It seemed to run fine, but I did hear some pinging under load (pulling tree stumps) once, so I switched to premium (90 octane here) and some techron cleaner twice a year. As gas prices go up, the cost of premium, if it remains $.20 more than regular, gets proportionately less, if that matters. I just have to leave the beast home for most long trips until I can get it paid off.

[reffug]

I always run what the manufacturer recomends for a given vehicle. Remember they spent millions in R&D and engine development so they should know what is best for a given vehicle. Just 02

[2000TLC]

Originally Posted by jjbodean1970

premium was only recommended for the 1998 to 2000 models, 2001 and up regular is the recommended fuel according to the factory

Then why do you guys think the factory made a change in the manuals stating that it is okay to use lower octane gas on the newer models? Aren't the engines still the same? Maybe newer technology?

[2000TLC]

Originally Posted by
My $.02 ( uninformed) - The ECU might adjust very quickly to the lower or higher octane level just as it does temp/air density ect...( in fact I doubt it measures octane independently [no octane sensor

but calculates it from other known variables) The only area that it probably takes time to adjust to is to driver imputs so that a temporary wild streak or driver change doesn't rapidly alter the vehicle's "feel" to the driver.

I agree with your $.02. I think the ECU would make a quick adjustment for the fuel that a person is using. I do enough city driving, that from stop light to stop light, I do not notice the few horsepower loss that I might be losing with lower octane.

[NMuzj100]

If the engine is running 2,000 rpm then that is 8,000 (?) combustions per minute to monitor. That is a lot of feedback and I expect that the the adjustments even if gradual to the computer add up quickly to find optimum settings.

[Kalen]

I found this article on Consumer Reports written September 2004.

Here's the link:
http://www.consumerreports.org/main/...East_id=333137

It reads:

"Paying for premium gas can be a waste of money

Many people use premium gasoline in the belief that it's better for engines than regular. That can be a costly mistake, especially during times of high fuel prices. Octane grades don't represent a “good, better, best” choice; they simply measure the resistance of fuel to knocking or pinging, a condition in which gasoline burns uncontrollably in the engine's combustion chambers. Knocking and pinging can damage an engine.

While high-octane formulations resist knocking better than lower octanes, most engines are designed to take regular gas, which has an octane rating of about 87. Engines requiring premium gas are typically the more powerful ones found in sports and luxury vehicles. Those engines use a very high compression ratio, making them more vulnerable to knocking, so recommended fuels have octane ratings of 91 or higher. Using premium gas in an engine designed to run on regular doesn't improve performance.

Some engines for which premium gasoline is recommended can run on regular without problems. That's because the engine's knock-sensor system detects the presence of uncontrolled burning in the chambers. When it does, the engine's computer-control system retards engine timing, eliminating the knock but slightly reducing power. If you don't mind giving up some performance, you can run these engines on less-expensive regular gasoline. To check whether your engine is capable of running on regular gas, read your owner's manual or ask your dealership's service department.

A hot-running engine or one with deposits may also knock, but premium gas may still not be the best solution. Service a hot-running engine as soon as possible, and handle deposit buildup with treatments that dissolve them. The treatments may be less expensive than regularly using premium gas."

I have an 2000 LC. Because it has a knock-sensor system that adjusts to the fuel octane, I decided to try running on regular unleaded gas instead of premium gas to see what it does. I felt really guilty putting it in the truck at first but I've run it for about 2 months on regular unleaded now and have not noticed any difference in performance.

The LC is still running smooth and strong. Gas mileage has been the same ranging from 13.5 - 15 MPG. This was the same mileage as I got when I only put premium in the tank.

[Jim_Chow]

I'm with DMX84. Use the recommended octane. If it's premium, what's a couple of extra bucks a tank when you're driving a $55K vehicle? Not only that, use high quality gas..brands like shell, mobil, chevron...not unknown cheapie gas from a ma-and-pa station. I heard toyota has traced a complaint w/ some camrys failing to poor quality fuel.

[NMuzj100]

The idea that a brand name gas is any different from any other is bogus. Gas quality is goverment regulated (during a refinery visit a Petro Engineer told me that there is little leeway for formulation and it all ends up the same) and in many cases the exact same gas is marketed by all the retailers in a given area because there is only one cost effective supplier (also has the funny effect of allowing them to all change prices at the same time). Notice that you rarely see a gas truck with a majors brand on it. Thats because then consumers would see the Chevron truck pour gas into the tanks at their local Texaco. There may be minor differences in additives added to this base gas ( this is why the big retailers usually advertise on additives or beer prices rather than the quality of the base product).

Bad gas is really rare in the US and is usually related to storage issues. A busy station is better than a slow one whether mom and pop or a major chain. On the other hand If the resupply truck is at your fuel point or just arrived find out from him which tank he is not filling and use pumps running off that tank. Refueling the tanks stirs up all the sediment and other contaminants in the storage tank. For jet fuel we would let a tank sit 6hrs to settle but contamination with gas is a much smaller problem.

Toyota claims that the fuel filters are good for the life of the vehicle but I plan on changing it out at 100k and inspecting the contants whether it needs it or not.

[jjbodean1970]

Originally Posted by NMuzj100

Thats because then consumers would see the Chevron truck pour gas into the tanks at their local Texaco.

actually, that happens all the time since Chevron and Texaco merged and are now the same company!

[NMuzj100]

Ok, Bad example. I finally get the one-finger (or is that two ?) salute on this board. But I doubt you see many Branded trucks on the road anyway. Does that mean I get "Techron" in my Texaco ?

How about a BP truck loading fuel at Texaco. Here in ABQ all the gas sold is refined at a Giant (local Co) refinery and resold by the Majors and independents.

Gas is a featureless commodity and should be purchased on price so long as there are no obvious worries that it has been spoiled since refining.

[hank14]

For clarification- where exactly is the fuel filter? I though it was in the gas tank, attached to the fuel pump, which is accessed only by remiving the double wide second row seat and the access cover under the carpet/floor.

[Kalen]

The fuel filter is a black canister that's bolted outside of the engine on the driver side of the engine compartment.

I was told that they do not need replacement by the Toyota parts counter, but a Toyota mechanic says he didn't believe it.

It's not that expensive and easy to access, so I replace mine at 115K mile during a major maintenance anyway.

It could just be psychological, but I thought the LC ran smoother afterwards. (Then again, I had all my belts, water pump, spark plugs, air filter, oil filter...ect changed at the same time.)

[hank14]

Thanks. I guess I was thinking of the fuel pump only, which I considered replacing when I was having some low idle problems. It turned out to be the throttle body needed cleaning- an easy fix. I'm going to order a new fuel filter. It's one of the many things I have had difficulty finding in my factory service manuals. To me, they are as clear as mud.

[Pitbull]

Originally Posted by Kalen

The fuel filter is a black canister that's bolted outside of the engine on the driver side of the engine compartment.

I was told that they do not need replacement by the Toyota parts counter, but a Toyota mechanic says he didn't believe it.

It's not that expensive and easy to access, so I replace mine at 115K mile during a major maintenance anyway.

It could just be psychological, but I thought the LC ran smoother afterwards. (Then again, I had all my belts, water pump, spark plugs, air filter, oil filter...ect changed at the same time.)

Replaced the fuel filter on my 80 at 100K miles and it didn't need it based on the condition of the old fuel filter. I would not waste my money again.

[Jim_Chow]

I had my fuel filter replaced at 125K...couldn't tell any difference vs. before/after. Just replace it for peace of mind. At least you'll know your injectors are less likely to get clogged.

[psfpilot]

www.toptiergas.com

For information about why some brands of gasoline are theoretically better than others.

[tabraha]

15,000 miles per year, 15mpg, .$20 more per gallon = $200 a year more AT MOST.

Now lets assume you lose 1 little mpg for going with the dirt. Without a doubt you will, if not immediately then over time.

At 15,000 miles per year, and a change grom 15 to 14 mpg, you would use 71 more gallons. At $2.20 a gallon, that's $156.20 in extra gas. So if you only loose 1mpg, you would save a whopping $43.80 over the course of a year.

Also consider if you put the engine under load, as in hauling or pulling steep grades your gonna loose more than 1mpg as the engine will want more bang from the gas but won't be able to get as much. It will have to work hard for longer because the ECU will be running in a watered down mode.

Our LX routinely gets 15-17mpg, with most of those being 17mpg. I have had to put regular in it before and when I hit the hills I knew it. I run the same stretch of interstate on cruise control at 68mph with the same 6 adults every weekend during football season. I get 16-17mpg and the vehicle pulls every hill without downshifting. With the regular gas, same people, cruise on 68mph, it downshifted (screaming) on at least a third of those hills, and my mpg was around 13mpg. All that fo