Hi everyone. I recently acquired a 93 LS400 that had been neglected by previous owners. I have gone through several fluid changes and the car has been running a bit better. I have gone thorugh an AutoRX treatment and am in the middle of the rinse phase. The AutoRX has helped! The recommended factory fill for the oil is 5W30. At this time their is no oil leak. I have been useing Delo and Delvac 15W40. My question is if I use a 5W30 will that oil shear to a XW20 after a thousand miles or so and if so is would there be an advantage to using a synthetic 0/5W20 or even a 5W20 dino? There is also ticking sound coming from the engine. The car has 125K miles on the clock. Is this common for Toyota V8s?