Good oil and proper OCIs seem critical. My GS350 has a dual injection system (High and low pressure injectors). The high pressure pump is driven off the camshaft. The place that sold it to me said a 5K oci is critical to keeping the car running well. The filled it with PP synth HM and said not to use anything else. I did some research and that seem to be the case.
http://www.underhoodservice.com/7-reasons-direct-injection-high-pressure-fuel-pumps-fail/
http://www.underhoodservice.com/7-reasons-direct-injection-high-pressure-fuel-pumps-fail/