My rx300 had an oil leak between the engine and trans (main rear seal leak).

Was running on semi synthetic oil. Leaking a few drops of oil on the driveway wherever it was parked and always a drop hanging, didn't really use much oil.

Replacing the oil with Castro Edge full synthetic 5w30 fixed this problem. At first the leak is a bit worse. Then overtime (about 6 months or so), the oil either cleans up the seal or conditions/expands it, or both. No more leak

Worth a shot.

Yep…. once again I'm pouring good money into a lemon. I got 4 bids ranging from $4000 to $900. I never take the cheapest or most expensive so I went with a referral. Took them over a week to get this done. Was a $7.50 part with the remaining cost in Labor. Yes, you read that correctly. The engine had to be completely pulled to get this one fixed.