DaveGS4

iTrader: (2)

Nick,

I invite you to use the forum's search feature to find answers to commonly ask questions such as this one

I searched for keywords ' regular premium' in the RX forum and found these right away among others

https://www.clublexus.com/forums/sho...remium+regular
https://www.clublexus.com/forums/sho...remium+regular
https://www.clublexus.com/forums/sho...remium+regular
https://www.clublexus.com/forums/sho...remium+regular
https://www.clublexus.com/forums/sho...remium+regular

cykodad

I noticed the RX 350 shows that you should be using Premium Gas, octane 91.

Isn't this the same engine found in the 2006 Rav4 and 2006 Avalon? They both show standard gas usage, octane 87.

If these are indeed the same engines, why the difference in octane requirements?

Tammy

They're not the same engine... They are Toyota and your's is Lexus.

The compression and power is more with your engine; so, the 91is needed.

cykodad

Isn't Lexus a brand used and owned by Toyota?

All 3 engines are very close in spec, 1 HP difference, and within 5 ft-lbs on the torque.

tfischer

Lexus is a division of Toyota.

Some frames and engines are used in both lines (e.g.: the RX330/350 has the same frame as a Camary), but this is a far cry from that deal in the 50's and 60's when GM would change a grill to change a Pontiac into a Chevy.

Even if different cars are using the same basic engine block, I think they are tuned and tweaked differently for the different weight of the car, etc. (But I'm no engineer.) Since Toyota does not sell gas, it has no interest in recommending anything other than the optimum octane rating that will perform best in any given engine. I generaly use the octane recommended by the manufacturer of my car rather than an octane recommended by the manufacturer for an engine I think bears a resemblance to the engine in my car.

PS: I used to have a RAV 4 and it's nothing like any Lexus on the road.

CK6Speed

iTrader: (1)

While it may be virtually the same engine, they are tuned differently. Different powerband and such. To get the optimum power out of your RX350 engine use Premium as called for. The car will still run on a lower octane at possibly reduced performance. Most modern cars today have knock sensors. They listen and detect engine knock and reduced ignition timing to prevent engine damage. That is why it is okay to use lower octane gas. it is all trial and error though. Each car is not the same and not drivin in the same coniditions, therefore, some people may have virtually no performance reduction when using lower octane gas and some people may notice a diffference. Personally, our RX330 gets its best gas mileage using premium fuel, so I stick with premium. Others don't notice any diffference at all so they use lower octane gas. All you have to do is try it for yourself and see which gas works best for you and your car under the driving your driving conditions.

Battousai

according to my sales person, he said I can use 89 on my RX 350.

tfischer

You can use 89, and the engine will adjust for it. Two points is well within the ability of the electronics to do whatever they do to eliminate ping and knocking. (The engine will probably "run" on 87 if you fill up with that.) On the other hand, you will generally get both better performance and better MPG with the 91.

Also, you can mix the octane ratings in your gas tank by filling up at the half way point with a lower or higher grade octane. Sometimes I'll do this around town, but not if I have a highway trip in the near future.

Lil4X

I've been doing a little research on fuel consumption on my 330. In a mixed cycle of urban/freeway driving, I seem to be getting about 18.8 - 20.0 on regular (86 octane) gas. When I bypass the 91-octane mid-grade and go for the full 93-octane premium, I generally improve that figure as much as 2 mpg. If true, the additional 20 cents per gallon is saving me roughly one gallon per tankful, or about 20 miles. So the cost of premium is pretty much a wash.

My Lexus dealer and service department have independently confirmed this measurement - that you get slightly better fuel efficiency with premium because the ECU is programmed for it. Knock sensors will allow your engine to use regular gas, but there may be some hesitation as the ECU has to deviate from the maps to eliminate knock.

As of June 1, local gas stations are now selling E10 gas exclusively. The substitution of ethanol for MTBE in the fuel blend has notched up the price a bit, and is likely to lower mileage - as ethanol has a lower specific BTU content than gasoline.

BTW If you want to experiment with blending your own, mixing grades of gas is perfectly acceptable. Some dispensers (pumps) still deliver mid-grade fuel by mixing regular and premium 50/50 during delivery.

CK6Speed

iTrader: (1)

Same here. I stick with premius because it does give me the best overall performance and I get the best fuel economy from it.



I'm starting to find this out myself. Our state for the first time as of 4/06 is using E10 in all pumps. The first thing I noticed was a drop in fuel economy by about 1-2 MPG (Depending on which car). IN stock form my RX330 used to get a combined citiy/highway mileage of 22 MPG. When I put on the larger 20" rims, it dropped to no less than 20 MPG. I never fell below 20 MPG before. Ever since we got the E10 gas, it has dropped as low a 18.XX MPG.

Like you mentioned above, the better fuel mileage pretty much washes out the $0.20 more you pay for premium. Even if there wasn't any fuel mileage increase with premium the yearly cost for me is only $156 more for premium each year. I call that two golf games and couple of Starbucks drinks

tfischer

You forgot to mention that the E gas also cuts down your cruising range.

Are there any advantages to this stuff?

Lil4X

Ethanol advantages? Well, for one it’s a renewable resource, grown and distilled right here in the USA – so you’re not making some desert sheik’s Mercedes payment for him. Second, it does burn cleaner – and may slightly reduce carbon deposits (remember it’s still only 10% of your fuel). It is replacing MTBE as an oxygenate additive – as MTBE has been proven to be a threat to ground water – so we get a double benefit – cleaner air and cleaner water.

For the long term, while ethanol can be used in fuel cells, its future is probably limited. Yes, it uses the sun’s energy to produce the fibrous plants that we ferment and distill to produce alcohol – but when you consider the energy input to the process, to grow, harvest, process and distill the product, it isn’t quite such a sparkling idea. It is, however one step on the road.

Long term we need to look at extraction of hydrocarbon from our enormous resources of oil shale and methane hydrate. Our energy future will be a blend of technologies – and these two hold tremendous promise for the near future.

32kcolors

I've always known that the RX-330 takes regular unleaded, but last night when I was reading the manual I discovered that the RX-350 requires premium fuel. I thought it was weird as this change isn't advertised as one of the differences between the two models on various websites and such. If you are a RX-330 owner, which grade fuel do you use? I read that Lexus recommends premium fuel for the RX-330 for the best performance (although it doesn't necessarily require it).

4TehNguyen

iTrader: (1)

just keep in mind in a vehicle that requires premium and you put in regular you might get a mileage drop, which negates any $ savings you tried to get by putting regular, no to mention there are power losses and you might be putting out more emissions

USLEX

You actually do not experience any loss in fuel economy. That is a myth. The only thing you will lose is 5 to 10 ponies.