G'Day Scotty, I live in Australian and I have a 2011 Lexus RX 350 Luxury Sports 55,000 Kilometres on the odometer which are built in Japan, the transmission is a AISIN U660F 6 speed. I purchased this off my brother 2 years ago I am a retired HVAC Design engineer so I like to keep my vehicles in top nick.
I had Lexus change all the fluids through out the vehicle as I was lazy, this is when my learning curve came with sealed transmissions HaHa. Any one worth there salt knows only a bloody idiot would state fluid for life and sealed.
This was in our usual hot summer when they did all the fluids, so in winter I started to get like a whiney cavitation noise when in reverse, as the transmission warmed the noise seemed go away.
I live in Canberra and it gets below zero degrees celsius in winter, so with viscosity and the WS ATF condensing and LEXUS properly not following there own procedure could be the issue, when I questioned them about the procedure they were very vague.
So I did all the research on the AISIN U660F transaxle and redid the transmission procedure (which I think is a joke), in my industry you would be raked over the coals being that vague with technical details, I used all Lexus parts.
Then on the next cold day I started the car and the same noise, so what I did was added 600 mls more of the WS fluid that seemed to fix about 70 percent of the noise. I was thinking of adding a bit more but I would prefer some of you knowledge if I may and thoughts. My further thought may be a sticky or slow solenoid only opening fully when hot or something of that nature.I watch your videos as well I always believe old dogs can learn new tricks. Kindest Regards, Jim Noonan. firstname.lastname@example.org