I knew the 2zr-fxe only have VVT-i for the intake side so, I hoped the dreaded VVT-i rattle wouldn't be so bad. But, in the past few weeks, I heard the noise for one second, a few times during the first start in the morning. According to the Car Care Nut, the only way to solve it is to replace the cam gear. There's no way to prevent it from happening since it's a production problem. I change the oil every 5000 miles with 0w20 synthetic oil, there's not much else you can do. I'm wondering if it could be related to the red bullet solenoid. Of course, I kept the OEM solenoid, so I might try to put it back to see if it change anything.
I have a 2015 (180k) and 2020 (30K). Both of them are prone to a little cold start rattle on cold, wet/humid mornings when I leave them outdoors. However, when I garage them, it never happens - not even one time. My garage is unheated and dry. I'm convinced the Prius start rattle is caused by temp/condensation.
Are you using a Toyota oil filter? You could try that. Especially if it is the cartridge type. Care care nut has a lot to say about those and the pitfalls if it’s installed wrong. Of course the oem solenoid too. I think some of the aftermarket filters don’t even fit right or are acceptable.
