Foster 525

I just joined Club Lexus 5 minutes ago and I will be taking delivery of a RX 350 next weekend. I just have 2 questions:

1. Can you shift the auto transmission manually (doing upshifts or downshifts) with the gated shifter, without causing any potential damage to the transmission?. I am coming from a BMW which had Steptronic Transmission that I loved.

2. Ist it okay to use 87 octane (if I am willing to sacrifice performance) without causing any potential damage to the engine.

Thank you.

CK6Speed

iTrader: (1)

I had always believe it was okay to do that, but some people disagree. Personally though, I wouldn't bother if it is not a real steptronic because the gated shifter makes going through all the gears a bit bothersome. I myself howshift a gear or two if I'm going up or down a steep hill, but other that that I just leave it in D and leave my shifting for my manual car.


Sure it will be just fine. Most modern cars have anti kock sensors that will retard ignition timing if knock is detected. If you don't mind the kock sensors potentially doing its thing feel free to put whatever gas in that you want. Personally, while I have never heard of a kncok sensor failure on any car ever, I still have that question in the back of my mind about what would happen if the knock sensor system failed and allowed engine knock to occur?

tfischer

You can use lower octane, but if your goal is to save money you will find that the lower MPG you get with the lower octane is offset by the lower price. Also, you will find that the lower octane gives lower engine performance, so it's like wasting a portion of the engine size you just paid a lot of money for.

As for the shifting, the 350 is a luxury SUV, not a performance sedan and certainly not a sports car. As the post above notes, all that shifting stuff is a thing of the past. I've owned and driven my share of sports cars and zippy little sedans with all kinds of transmissions, and you just don't want to drive that way in a car the size of the RX. It's not designed for it.

4TehNguyen

iTrader: (1)

you would get a check engine light if knock sensors failed, all cars should be like that

using regular you might lower your mpg and negate any savings over premium, plus the car wont be as responsive as it will be with premium

spikerjack

Can't speak to the manual shifting.....but I can't think of a reason in the RX 350 that I would want to do that - as its very responsive to pedal action AND its not what I wanted this particular Lexus model for.

I --can-- speak to the fuel issue - I started with 87 octane for the first 800 miles or so and then switched to full premium. Now have about 3800 miles. Both the performance difference and the MPG difference was noticeable after the switch. I would strongly recommend, however painful, to get the max out of your RX350 and go with premium.

--Scott

Booyah

Should have went for the optional performance package with the air suspension and a shifter made to bump up/down in the gears----I like that feature in mine

TunedRX300

I find it is ironic to talk about performance of that premium gas can give and not gate/sequential shifting in the same paragragh. Leaving the shift pod at "D" will result in >50% "haircut" in horsepower from max, using premium will result in low single digit % (if any) gain. That is >10x difference in performance. I can understand people want to put premium gas for other reasons, but performance is probably the most "over-rated" reason.

If one pays attention to RX300's technometer, leaving shift pod to "D", 99% of the time the car will never hit >3000rpm. The horsepower delivered at wheels are not 220 horsepower, in fact, RX delivers a meager 94 horsepowers. Even less power is delievered at 2500 rpm (typical cruising speed) .
Take a look at a dyno graph of RX300 AWD

The dropoff is caused 1) powertrain loss of 20% when the power is delievered from the crank to the wheels 2) max power is at 5800 rpm, at <3000 rpm, there is a significant drop off.
One can do little on cause #1, but sure can use gate/sequential shifting to avoid cause #2 during acceleration - simply control the engine to operate at the sweet RPm range of power band.
Now how many RX300 owners ever get the engine up to 5800 rpm? With RX350's peak power is at even higher RPM of 6200, leaving the shift at D, RX350 will likely get that >50% haircut again from its peak power rating. Now that is leaving a lot of HPs on the table while spending $0.20 per gallon on premium, IMHO, it is the least economical way to achieve performance.

CK6Speed

iTrader: (1)

I don't think anyone said you get added performance from premium gas. I think we all know by now there is nothing magical about premium gas that would give you additional performance.

Also, the last time I tried flooring the gas pedal our RX330 shifted way pass 3K RPM. Sure, in regular driving it shifts low and economically, but it still shifts at redline as far as I recall when you floor it. Even in my manual trans sports car I don't shift at redline all the time. During regular driving I usually shift around 3K RPM just like the automatics. I just don't see why shifting manually through the gate shifter in a NON steptronic trans during regular driving will be of any benefit.

TunedRX300

I never get to redline with RX300 by just leaving at D, I achieved a couple of times of 4000 when I go WOT, but that is a "feature" provided by the famous hestiation issue of RX300.

hmm....here are two
By no way I say you should gate/sequential shift, but the logic is little off if one try to gain <5 HP while leaving >100 HP at the table. I am sure there are other stronger reasons for premium usage, but performance, IMHO, is the weakest one. $0.02

CK6Speed

iTrader: (1)

I agree there. I simply use octane as a gauge for knock resistence and not performance.

Nostics_RX

It boils down to the "feel of the beholder." If you feel like the car is running smoother and better with "premium fuel" and you feel good about it...it's well worth it. I personally use "premium" but if money becomes tight, regular will do just fine with me. Consider your self lucky for driving a luxury SUV that can run on "regular" if need be. I'm sure it will come handy. Just my opinion.