Thanks for all the advice.
Yes I did get a carfax at purchase and the condition of the vehicle did not indicate more that 16k. Who knows? but its hard to tamper with the reading. The car fax gave only original purchase and annual registrations. The sludge is caused by failure to drive far enough to warm the car up and burn off the condensation water that collects in the engine as at cools. This is a further indication that the milage may be correct. Lexus is prevented by law giving the former owner's ID here in Fla. Most used cars do not carry service records, perhaps 5% do.
I'm proceeding to court with the engine was defective in design or manufacture, supported by the 3 million cars (Toyota and Lexus) repaired in the class action settlement sludge lawsuit on the 300 engine earlier RX model.
My second arguement is that the Lexus experts, who know the car best made no request for service records when the car came off lease. They never considered sludge damage could occur at 16k, It should have never happened except the engine has a design weakness.