Anyone have any issues using regular rather than premium?

 

I have used regular gas in cars that have either recommended or required premium for over a million miles and I've never had one single engine problem.. I have a 24 RX 350H now and I've always used regular. In experimenting I've noticed no difference in gas mileage or more acceleration. Go out to YouTube and search CBC octane test. They did an in-depth study on premium and regular gas and confirmed exactly what I said there's absolutely no difference in engine wear, gas mileage or acceleration. Having said all that use whatever you want.

 

Premium for our first tank, Regular ever since.

350h manual specifically says:
Compared with the 350 and 250:
Note which is the minimum rating before they state "damage to engine may occur". 87 for 350h and 250, 91 for 350.

Lots of posts here on which gas to use, I don't think there's a single post from someone who has used 87 instead and regretted it.

 

There are 3 potential reasons to use premium in any car.

1) Octane to reduce knock/pre-ignition. I won't even discuss this part because it has (and will be) discussed a million times.
2) Detergent additives. Many brands of gasoline meet "top tier" status which dictates a certain level of detergent additives. Many gasoline brands will "exceed" these minimums for their premium fuel, and "possibly over the long term" result in somewhat cleaner engine internals. This isn't a specific property of premium fuel per se, just that some brands will offer this included with their higher octane fuels.
3) Friction modifiers. Some gasoline brands will offer friction modifiers in their higher octane (aka premium) fuels, but again not indicative of all premium fuels. One of the downfalls of engine oil is gradual dilution of oil by fuel. As oil becomes diluted, its viscosity slowly drops and its anti-friction additives reduced. The level of fuel dilution is at maximum right at the piston rings where they are directly experiencing maximum pressure and maximum contact with fuel. Friction modifiers in the fuel will reduce piston ring / cylinder wall wear and "possibly over the long term" result in better maintenance of cylinder compression and performance.

So 1 is definite a thing. If you car requires premium, its certainly a very good idea. If your car recommends premium, it may or may not be good depending on your driving characteristics.

2 and 3 are not a "premium" thing. You don't get them by filling up with any old premium fuel. They depend on the brand specifically, and also yield possible benefits over many years, not over the tank of gas. And there's nothing to say that some brands might offer these features in regular fuel as well, its just typically more likely to be added to premium. If 1) doesn't apply to you, 2) and 3) would be considered optional upgrades if you really really car about your engine over the very long term. Anyone leasing or already have a trade in date in their mind as soon as they get their new car this probably has zero benefit for them.

 

I used regular 87 and regretted it because my billfold became too heavy. Regular even works well in my 2.3L twin scroll turbo.

YMMV,
MidCow3

 

Agree with all commenters. My rule of thumb is always use major name brand fuels, no Bob's Big Boy discount fuels for me.

I have a 350h and it's seems logical that if you're not using or expecting all 240 horsepower from your engine, why feed it gas that will do so and then not use it? I'm ok with 230 hp . But well formulated high detergent gas I'm on board with.

One Option is look for a Top Tier sticker at the pump or do some homework here:

Top Tier gasoline : https://www.toptiergas.com/about-top-tier/#sponsors

Evidence of reduction in engine wear with new fuel additives now available in premium fuels:


In RX forum someone had determined that in his 350 he was using cheap gas and began experiencing a short stumble upon initial tip in especially when trying to 'get moving fast' . Switched to good fuel and it went away.

 

I drive a NX350, so it requires premium gas. I asked my salesperson to explain why. He said "if you can't afford premium gas, you can't afford a Lexus".

 

Lately, Mazda has been publishing that in their turbo engines if you use regular gasoline 87 octane you will get XXX horsepower, along with slightly less mileage. Putting in their recommended 91 octane fuel you will get higher XXX hp and slightly better gas mileage. With no other mention that the regular fuel will do any harm to your engine. I would deduce from that, as every automaker has the skills and abilities to wring out every possible mpg and hp they can out of their engine designs, that Toyota engines and all others will follow along with this statement in their designs. Yes Toyota and Lexus do not come forward and state this per say, but as with Mazda, their turbo engines will take regular fuel and provide less horsepower and most likely worse gas mileage too. As Toyota engine designs almost always use their D4S injection system you don't have to worry about carbon build up on the valves and intake runners as well.

So it's the owners call I would say, do the math and figure the $ at stake here. I really don't think any mechanic could tell you that because you used regular gas you did this .... damage to your engine.

 

That is such BS!!

Edit: I meant to add my reply after quoting this: "I drive a NX350, so it requires premium gas. I asked my salesperson to explain why. He said "if you can't afford premium gas, you can't afford a Lexus". "

 

Why Thank You!

 

It comes down to the turbo part.
If your engine has a turbo, go with premium, as you will get the most power and efficiency.
If your car is not turbo, you can use a regular.

I recommend using Top Tier gas. That alone gave me 2mpg more, and I use regular gas (I have the 350h)

 

Wow, I'd have walked out with that level of condescension.

 

Thinking the same thing. I would have said that is why I can afford a Lexus. A rational consumer.

 

Actually not fully BS because there is some truth to Mazda says. With new ( you remember points and plugs and a distributor) electronic ignitions the software is able to advance/retard the ignition to a fairly wide degree and prevent pinging (premature detonation) when a lower octane gas is used. I have a 2.3 L twin scroll turbo ( 350 Hp, 350 ft-lbs torque( that will run very well on regular 87 octane ...it is somewhat comparable with the 2.4 L Lexus 350 NX turbo.

YMMV,
MidCow3

Ban turbo lag

 

Yes and ALL modern cars have a knock sensor to detect pre ignition or knock or pinging and make these adjustments ever so slightly just enough to stop the pre ignition. The pre ignition is truly your pistons 'slapping' against the piston walls! That's what causes the noise and it is very harmful to your engine over time. This use to happen all the time 'back in the day' of carburetors and points, and if you could just tweak your distributor cap position one way or the other and change your 'advance' of the spark timing you could eliminate the knock. As cars aged they would gather up carbon deposits on valves and cylinder heads since detergent gasoline wasn't a thing yet. And your car would start to ping when you stepped on the gas. So all your buddies would tell you - you gotta put in premium gas or move up to a higher octane. That is the only thing the octane number provides you with is the ability of the fuel to not ignite under light load but only when the spark happens. And because of this modern cars now have electronic or hydraulic timing advance systems to advance or retard the timing on the cam shafts providing you with the most amount of horsepower possible from the gasoline you are consuming. "Depending on a vehicle's engine design, octane plays a key role in engine performance and measures the ability to resist auto-ignition, which is commonly referred to as knock. As engine compression increases, so does the amount of power and efficiency generated by a given amount of fuel." Now if they've designed the engine for high compression and can advance the timing a little further than with regular gas you get more power! You put in regular gas instead of the recommended 91 octane and the engine will figure this out and provide you as much HP as it can get with that regular octane. Lower octane doesn't cause anything negative to happen to your engine except less HP being produced.

Cheap low grade non detergent gas wether it's regular or premium is harmful is your engine!