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Regular unleaded gas 2010 lexus rx 350

anybody try this or knows something about this? The manufaacturer recommends premium but just on the principle of the thing? thanks

The RX350 and ES350 use the same engine (displacement and compression ratio) as the Camry and Avalon. If the manual says ‘recommends’ you can try regular to see if it makes any difference in mpgs or hp. In my '96 ES300 it did not, and I have used regular for 15 years, no problem.

However, if it says ‘required’ then I’d stick with premium.

This question pops up on the board with alarming frequency. The answer remains the same. If you buy a premium vehicle with a premium performance engine, you have to feed it premium unleaded or risk severe engine damage. The damage will not be instantaneous, but it will happen over time. Using regular in this engine may result in pinging (preignition) under load, you will experience diminished performance, and you will experience lower fuel economy, which in itself negates any savings at the pump by using regular over premium. If you fill up with regular instead of premium, you will save maybe two or three dollars, but if you get 30 fewer miles out of that tank of gas, you have saved nothing and in fact lost money by trying to be frugal. The whole while this is going on, if you experience pinging, that noise is ill-timed explosions eating away at the pistons and combustion chambers inside your engine. Damage like this will make the pinging get worse, leading to more damage. Once the damage is severe enough, you will have to replace the engine to solve the problem, further negating your savings at the pump. In short, it’s not so much the principle of the thing as there being a very real need for a high compression engine like yours to need higher octane fuel to live. For future reference, if you don’t want to pay the extra 20 cents or so per gallon of fuel for premium unleaded, make sure the car you are considering spending $35k on will run on regular unleaded.

Mark, that’s simply not true if premium is ‘recommended’. It means that the car’s knock sensor will allow the timing to advance with premium, producing slightly more power and potentially yielding slightly more fuel economy. Ford now provides power ratings for both regular and premium on some of its motors, such as the new 5.0l V8.

If the maker says primium is ‘required’, then I would use premium. This is often the case with turbocharged/supercharged cars, or high compression cars.

I agree with the “required” versus “recommended” argument. I find it a little bizarre, though, how many buyers of expensive luxury cars think premium unleaded is too expensive and they need to save money by buying regular instead. Of course, according to Tom and Ray, no matter what the owner’s manual says, required or recommended, or the engine’s design specs, you can use regular unleaded in it with no ill effects. The difference in price between regular and premium is not worth the risk to me if the engine’s octane requirements require a higher octane fuel. Plus I can’t stand to hear pinging and knocking, even though some companies now say preignition is perfectly harmless (BMW, I think).

Personally even if Premium was just “recommended” I’d still buy it. If the knock-sensor fails then you could be looking at a new engine. I agree chances of that happening are slim.

And with reduced performance and gas mileage I don’t see much (if any) savings by buying regular.

If it says recommended, why not just buy medium? It still has more octane than regular, but less than premium and cheaper than premium.

I don’t usually disagree with Tom and Ray, but they’re wrong here. A guy at work has the same year TL I do, but cheaps out and runs regular instead of the required premium. His car sounds like a popcorn popper every time he drives it. Pings like crazy. The ECU can only retard the timing so much before it’s out of wiggle room, and the engine is designed to run on premium. I guarantee his car’s going to die an early death thanks to his frugality, and he’s not even saving money because he’s getting 17mpg around town while I get between 22 and 24.

Recommends is far different than requires.

You may want to run a few tanks of regular and see if MPG remains the same. In my car requiring premium I get a drop in MPG that with today’s prices actually more $$$ than simply using premium.

An interesting fact about premium. As the price of gasoline goes up the extra cost of premium actually goes down. It has always been $0.20/gallon-$0.25/gallon more for premium whether regular has been $1/gallon - $4/gallon. So at $4/gallon you are paying less as percentage of gallon of fuel.

If your car requires premium, then it doesn’t take much for that switch to “regular” to be costing you more money.

As an example:

  • Premium costs 5% more than regular ($4.20 vs $4.00)
  • Say your car gets 20 mpg using premium. (Note: 5% of 20 is 1 mpg)
  • If that switch to regular drops your mileage by more than 1 mpg,
    then it’s costing you more to use regular.

So aside from the drive-ability and potential engine risks that others have mentioned, make sure you really understand how much money a switch to regular will really save you (or cost you).

Am I the only one whop thinks the type of gas required should be disclosed somewhere on the car, like the dealer sticker? You read that it gets 17/24 mpg, and in letters as big as those numbers, it says “requires premium fuel; you’ll damage your engine if you don’t use it, and you void your factory warranty if you do.”. Bet they wouldn’t sell as many high end cars like that