You said the oil is topped up and clean? How much oil was put exactly ? It sounds like there may be too much oil, which is creating a burning effect, therefore exiting via exhaust. I'd get a professional mechanic to drain the oil, then replace oil within the specifications required for this engine size.
Test only, sorry not used to this format
Thought I'd found someone else with my problem but not to be. My IS200 (2003,70000km) blows about five seconds of blueish - whiteish smoke when started each morning then is ok until the following morning when said smoke appears again. The selling dealer (non Lexus) assures me that the problem is Throttle body cleaner which they used when servicing the car still remaining in the intake manifold but seems a bit far fetched to me. I'm hoping they're right as the car is still under statutory warranty and I don't relish the idea of them delving into the Lex engine room. What do you think ??