2.4 L 4 cylinder turbo engine.
TX350.
Emulsified oil is a mixture of oil and water.
Water in an engine is usually not a good sign.
Oil cap has lots of milky sludge on it.
Anyone else notice this ?

 

Nope. Not with my 2023 RX 350 (15K miles) or 2026 TX 500h (1600 miles).

Sounds a lot like a blow head gasket, though there are other possibilities. This needs to be addressed ASAP by a good mechanic before it can cause further damage.

What year is the car and how many miles?

 

Lexus dealer states that they have been receiving many such complaints and that the frigid temperatures are to blame and that I shouldn’t be concerned.
For over a month, it’s been extremely cold which causes condensation in the valve cover.
2025 TX350 has 55,000 km. (34,000 miles).

 

Check the dipstick every full up while you still have warranty for any milky substance.

 

AGREED! Any milky oil on the dipstick (in particular) is cause for serious concern. And make sure the dealer notes your exact concern in their maintenance log, in case this later leads to bearing failure. Any milky oil on the INSIDE of the oil filler cap is STILL cause for concern in my book. I lived in the northeast for decades and lived through MANY cold winters, and never noticed "milky oil" (water in oil) on the INSIDE of the oil filler cap in any of my cars. Given the ultra tight bearing clearances in modern Toyota/Lexus engines, any significant amount of circulating, emulsified oil is unacceptable, IMO.