I recently bought a used 2006 LS430. Called the Lexus dealership in Dallas that did the first three oil changes and they said they used regular Mobil 5W-30. The Lexus place I took it to in Houston put in a Kendall synthetic blend. I have to have the oil changed every 5K to keep the powertrain warranty. I will only put 7K-8K miles a year on the car. For the next oil change coming up (25,000 miles), should I go to a full synthetic like M1 or PP, or just use a regular oil like Mobil clean 5000 or Pennzoil YB. I plan to keep this car for a long time. Even after the warranty is out, I will still change the oil every 5K. Thanks.