It was really cold yesterday here in Southern Ontario Canada yesterday. The RX330 was in the outdoor parking lot all day with temperature below -10 degree celcius. When I start the engine the engine sound was very loud especially after I shift it into reverse and drive and the car is still stationary. It almost sound like an old vacumn cleaner. It was less loud when it was in park and neutral. The engine noise level return to normal after I drove it for about a kilometer. The RPM was not particularly high. Any similar experience.
Ken
RX330 multipanel moonroof

 

The motor oil was probably getting thick at such low temperature, thus the noise. Try use 0w30 oil or synthetic oil if this car is going to be parked outside often. And give it a longer warm-up time before driving off.