Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Regular or Premium

I recently purchased a 2008 Totoya FJ Cruiser. The manual states to use premium unleaded fuel. Further down the manual, it states you can use regular if you cannot find premium. I have been using regular and it seems to run fine. Any longterm concerns?

the manual has told you what to use. what octane does it specify? 91 or 93?

the regular is only for when your alternative is to run “out of gas” until the next tank.

how much did you pay for this sled? like $45,000 and you are quibbling over the difference in like $3.50 per fillup???

without getting into the reasons that a lower octane can harm your engine, (some of the other posters are much more eloquent than i about the tech end) toyota has specific reasons why you are supposed to use premium. they wouldn’t say use premium just to boost exxon mobils profits.

What is your definition of long term? I can imagine a vehicle like a FJ Cruiser it will be traded off in 3-5 years so it probably won’t matter during your ownership period.

Check you MPG using regular for a few tanks then required premium. See if the meager $4/tank is worth saving as you likely will lose MPG using regular.

You should use unleaded premium until the warranty runs out. This is just one more way that Toyota could void your warranty if you have engine trouble. The ECM will retard timing to allow you to use regular unleaded fuel, but that will mean lower power and might mean poorer gas mileage. You paid at least $23,000 for your FJ. An extra couple of bucks per tankful is cheap insurance against any long-term problems. Toyota designed this truck to run best on premium fuel. Neither your nor I know better than the professionals at Toyota how to operate this truck.

I’ll give you two examples and then you can choose. I have a 68 muscle car (OK, I’ll admit. The engine was rebuilt with high performance parts). When I try to run cheaper gas in it the engine rattles, pings, and re-detonates. I have an 03 GMC luxury car that wont run any better if I use expensive gas. Cars these days are built to run on whatever gas you put in it. The manual will also state that you must always have your car worked on at a Toyota dealer - just depends on how much money you want to give up.
Moral of the story: the liberal and his money are soon parted.

Your rig is what’s called a “premium recommended” vehicle. Unlike a “premium required” vehicle, the computer can effectively “de-tune” the engine to make it run on regular. However, in this day and age gas is pushing four bucks a gallon, but the difference between regular and premium is still only 20 cents or so-- I can practically guarantee that your mileage will improve enough on premium to cover the cost difference.

You need to carefully read that manual. There are three classes of gasoline cars. Those that NEED premium to prevent problems and those that should have premium, but if you use regular you will not hurt it and finally those that should use regular.

If it really says you need to use premium except maybe those few times that you can’t get regular, than you risk damaging the engine by using regular.

If it recommends premium, then switching to regular will reduce the mileage (how much varies a lot from car to car and driver to driver) and it will reduce performance.

If it says regular only, using premium WILL NOT increase performance, or protect or clean the engine, but could actually damage the engine. Not likely, but possible.

I suggest you should check before buying your next car and factor in that additional cost before buying.

While searching on this topic several months ago, I saw it said on the Internet that there are some modern vehicles with knock sensors of course, whose owner’s manuals specify 87 octane fuel, but can advance the spark timing to take advantage of premium gasoline. Not all but some. I’m going to try it during an upcoming trip. If true, this would be a 4th class of vehicle per the list provided.

That would be a premium recommended vehicle. The Astro van I drove for work a while ago was like that-- it said it was okay to use regular for just driving around, but it was required for towing. And it did get slightly better gas mileage using premium.

How dare you compare a finely tuned machine that makes music as it gets from a to b to some computer controlled widgit that could likely tune itself to run on a good corn whiskey. Oh, for a 400+ cubic inch jukebox with 11:1 compression, a beasty bumpstick, a pair of quads, and maybe some 3 inch pipes. Hell Yea.

The answer is a question. Can you find premium? If you can, you use it.

Mine is a premium recommended vehicle. I have run it both ways. I can detect extra pickup with premium–a little–but absolutely no better gas mileage under normal driving. So I use regular. I might use the premium if I were doing a lot of hill climbing, or trying to outrun people, but I’m not.
If it says premium required, run premium.

I dunno why I still have that album on my site, guess it’s just for nostalgia after I sold it. 65 chevelle 283 with dual glasspacks

Manuals only recommend dealer for every make. Its illegal for them to state ‘that you must always have your car worked on at a xxxxx dealer’ unless work is free.

Right now (mid May) is running a CNNMoney article “6 gas-saving myths” (also on They emphatically state that if a car’s maker recommends premium (but will run on regular), you should never buy premium. They say that there will be no performance penalty in normal driving, and no mileage penalty, to run on regular. That is contrary to what comes up every time in these discussions here. Who to believe?

Don’t be misled that you’ll always save money by buying regular fuel for a car designed to run on premium. The “detuning” that is done to allow the car to run on regular can quickly eat into the money you saved at the pump.

For example, if you have a 20 gallon tank, get 20 mpg, and are paying about $4.00/gallon for premium, and can save 20 cents/gallon with regular, then all it takes is a 1 mpg drop from using regular to eliminate all the money you saved at the pump.

Specifically, you would save $4.00/tankful during your fillup at the pump by using regular. But if your mileage drops by 1 mpg, then you’ll need an extra gallon to drive the same distance that a tankful of premium would have taken you. Now, not only are you not saving any money, but you’re getting less performance and pickup from your engine.

Here’s the CNN gas mileage myth article:

I have to disagree with at least one of their points. How can a clogged air cleaner being replaced NOT improve your gas mileage? The engine has to get air from somewhere so that the fuel-air ratio can be maintained at about 14:1 by weight. If the air filter becomes say 90% clogged, no amount of computer compensation will be able to make it right.

The restricted air cleaner will change the amount of air/fuel mix that can make it into the engine, but it will not change the ratio or air/fuel any more than pressing on the gas pedal will. A doubt if a car with a 90% clogged air filter would be very drivable, but it likely would not suffer greatly from the stand point of mileage.

I would suggest that CNN-Money is not a good place to got to get car advice. CarTalk is not a good place to get investment advice.

So you decide, CarTalk or CNN-Money for car advice and CarTalk or CNN-Money for investment advice.

I think I know where I would trust for what advice.

I guess I will skip taking my car to the drive through Bank window for an Oil Change. You may feel otherwise :slight_smile: