Hello BITOGers I used to read this board religiously, but switched our cars to EVs over the past 5 years and thus I have been away from this place for awhile. We're switching out our extra third car to an 07 RX350 with the 2GR-FE engine. Going through the records the PO provided, throughout the 166k engine life, it has received mostly Toyota bulk 5w20 oil at the toyota dealership, and recently some shop's synblend 5w30. Motor does not appear to burn any oil, could not see any oil leaks, engine and underside looks clean. Since this is the third car and mileage will not be put on at a fast rate, plus the fact that the 2GR-FE is known to be a pretty resilient motor, I don't really care what oil I put in. But here's the rub - I had stocked up on a ton of BMW LL01 oils from my prior car, and I would love to use it. I'm talking like 25 qts of the good stuff - PUP, PPEuro, the magical elvish elixir known as German Castrol 0w-30, and a random old case of M1 5w30. I've had a pretty bad experience in the past of switching an e36 m3 that had been dino oil all its life to synthetic at 200k. I was chasing oil leaks left and right at that point. Given that, I'm tempted to not rock the boat and just keep on keeping on with dino on the RX. But, I've got all this good synthetic doing a whole lot of nothing, so I'm also tempted to just run the good stuff since I got it. But with a newborn and a toddler, I just don't have any time whatsoever to be chasing down oil leaks and replacing engine seals. Any advice would be appreciated.