Title says it all. Should I stick with a FWD or go AWD?

 

Depends if you need AWD. There are no reliability issues related to the AWD. They are not a weak spot on the RX.

 

From what I understand, and observed with my 2015 RX, AWD only works up to 25mph. at 26mph, it kicks off.

 

That is when you use the 4wd lock switch to get out of snow or a ditch. That is separate from the regular full time automatic AWD. It does shut off at about 25 mph.
The automatic AWD is truly automatic and the car is FWD 80% of the time. If it senses slip of the front wheels and probably the rear wheels then it will engage the rear drive to help traction.
My 2016 Toyota Sienna Limited AWD has the same system and a screen I can pull up to watch the AWD percentage activation while I drive. It does pull in the rear wheels a bit when acceleration, going around some corners or uphill or if there is rain or snow depending but it is mostly FWD. It is more like a temporary rear wheel boost to help traction.

 

I would say that the AWD system is reliable, however my 2015 have had an OEM replacement transfer-case installed before I purchased it a couple years ago with about 172k miles on it. The transfer-case aluminum case looked almost new compared to the other aluminum components like the engine and transmission next to it. Why my 2015 needed an replacement transfer-case unit is unknown.

My old 2011 RX350 AWD system is still going strong with less mileage. I think about 150k miles as per the current owner when I last checked. However, I did change the transfer-case fluid at around 60k miles before I sold it.

My guess is that the previous owner of my 2015 RX350 did not ever service the old transfer-case fluid well pass 100k miles and then it failed somewhere before 172k miles. So I assume that the AWD system is reliable if you change the old fluid in it before 100k miles and may have issues if you wait too long after 100k miles to service it.

 

So to clarify, the AWD system DOES kick in a any speed, if conditions warrant? But you can't command it to kick in at any speed, only below 26mpg? Does that sum it up?

Also, what does SNOW mode do?

 

It does kick in at any speed if conditions warrant. That is the automatic AWD system.
The button on the dash is to activate 4 wheel drive locked on to help you get out of tough situations at low speed. You have to toggle the switch. It then turns off automatically when you reach about 25 mph.

As stated better by AI:
​​​​​​The Lexus RX 350's all-wheel drive (AWD) lock mode can be used to send power to all four wheels when driving in poor traction conditions. This can help the vehicle build momentum at lower speeds.

How to use the AWD lock mode

1. Press the AWD lock mode switch while driving at speeds below 40 kmh (25 mph)
2. The vehicle will distribute power equally between the front and rear axles
3. When you're unstuck, you can manually turn off the AWD lock mode by pressing the switch again

When to use the AWD lock mode When driving in snow, When driving in mud, When driving in sand, and When climbing or descending steep hills.

How does the AWD system work normally?
The RX 350's AWD system automatically sends power to the front and rear wheels as needed. This helps to improve traction

Here are more thread discussions: https://www.clublexus.com/forums/rx-...-settings.html
https://www.clublexus.com/forums/rx-...ck-button.html
https://www.clublexus.com/forums/rx-...s-engaged.html

 

The AWD system is always active and adjust the power to the wheels as needed based on traction or wheel spin. The AWD lock allows you to lock the unit in 50:50 split up to about 26mph. I have used the AWD lock feature a lot yesterday during the snow/ice storm here in the Atlanta area. It work perfectly up to about 26mph and then the turns off. The AWD lock light will flash when going over 25 mph and the AWD lock light turns off.

The AWD system will still adjust for road conditions above 26mph. I just used the AWD lock feature when starting from a stop on ice and when pulling up icy hilly roads.

 

You can have your rx 350 in AWD at speeds above 26 mph by engaging ECT (Electronically Controlled Transmission) SNOW mode. This will keep your vehicle in AWD no matter what speed you travel at until such time as you disengage this feature. The following video illustrates how this can be done to engage and disengage AWD:
https://www.google.com/search?q=how+...U0XHJr7L8,st:0

 

SNOW MODE was my other question. The owners manual mentions it, but does not say what it does. Also guys, don't forget about HILL MODE. Sounds like that may help you out CarGuy75. You gotta love the owners manual, it goes into excruciating detail about how to lock your door, but doesn't mention what SNOW mode actually does.

 

^^The 2010-2015 AWD RX models do not have Hill mode, ECT or Snow mode. My model have AWD lock and traction control buttons only. My RX350 did not have any issues going up an icy hill.

Correction: I stand corrected. I do have the snow mode feature on my 2015 RX350 with AWD. I did not need the option as that my RX350 never lost traction even on the steepest hilly iced over roads. I do have Yokohama ADVAN sport A/S+ all-season tires mounted on my RX350. Damn good all-season tires that provided great traction.

 

The AWD system works in all speeds by default. The ECT Snow mode just reduce the throttle output and/or start the transmission in 2nd gear to reduce wheel spin(less engine power/torque). The feature is on other makes under different names. I did not know my RX350 had the feature in the "secret" menu as most other makes uses a button on the console.

The AWD lock feature just ensures that the AWD system provides traction to all wheels at all times. Without the AWD lock engaged the system may not engage all wheels until it detects wheel spin which may cause an abrupt change in handling on the ice. Hence why I engage the AWD lock when going up icy hills or from a stop on icy roads.

 

I tried it on mine one day, it works. When at stop light, just press brake pedal down a little further and it will engage.

 

I assume you mean hill mode? Good to know if my 2015 model does have that function.

 

I also did not know the 2015 had Hill-Start assist Control. The following is from page 276 of the Owner's Manual. Page 277 is also important to read.

2-4 Using Other Driving Systems
Hill-Start assist control

Hill-start assist control helps to prevent the vehicle from rolling backwards when starting on an incline or slippery slope.
To engage hill-start assist control, further depress the brake pedal when the vehicle is stopped completely.
A buzzer will sound once to indicate the system is activated. The slip indicator will also start flashing. (To add: there is a picture of what the slip indicator looks like on page 276.)

■Hill-start assist control can be operated when
●The shift lever is in a position other than P.
●The parking brake is not applied.
●The accelerator pedal is not depressed.

■Hill-start assist control
●While hill-start assist control is operating, the brakes remain automatically applied after the driver releases the brake pedal. The stop lights and the high mounted stoplight turn on.
●Hill-start assist control operates for about 2 seconds after the brake pedal is released.
●If the slip indicator does not flash and the buzzer does not sound when the brake pedal is further depressed, slightly reduce the pressure on the brake pedal (do not allow the vehicle to roll backward) and then firmly depress it again.
If the system still does not operate, check if the operating conditions explained above have been met.