Is it okay to shift from Drive mode to S mode when car is moving
 

Hey guys, just a quick question. I'd think its fine but just want to make sure here, is it okay to change from Drive mode to S mode while car is moving?
Like in the case of driving down hill when engine braking is needed.
thanks.

I hope so because I do it a lot

Yes. That's what you have it for. Partially. Don't expect much of engine braking though.

Always. They wouldn't allow it to happen if it wasn't okay.

As an alternative, you can down shift using the paddle shift (or move to manual then down shift) for more engine braking.

I don't think shifting to Sport mode would result in much engine braking, if any. Your idea would be better.

Are we talking about an RX350 or RX350F Sport?
Only the RX350 has the "S" mode on the Shift Lever.
The RX350F Sport has an "M" mode on the Shift Lever along with the Paddle Shifters
The Sport mode is selected on the round knob to the right of the Shift Lever and should not be misconstrued with "S" mode selected by the Shift Lever
FYI, I use the "S" mode a lot to down shift the gears to achieve engine braking. I have a 2018 RX350.

I think some of us misunderstood. Pretty sure OP is referring to S shift mode and not Sport drive mode.

You're right, I forgot about the S+/- on the shift lever. Now I'm not sure if the OP was referring to that, or the knob on the console?

Probably shift lever since he referred to engine braking.

Either way the answer is a big YES