Please, I am not trying to start another oil debate, only asking a question of those who have had experience is this area.
I am thinking about changing over to AMSOIL 20W-50 in my 1984 500SEL with 250K miles. Currently using Rotella 15-40 dino and all is well but I have read so much about the better mileage and engine life with syn oil. AMSOIL is hard to find, but is a true syn oil with a good reputation.
My experiences with syn oil in the past hasn't been very favorable in Domestic cars.
What do some of you think?

Thanks

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84 500 SEL (307,xxx miles)

As much Amsoil as I've used in the past I do like the stuff, but I'm kind of hooked on the Mobil 1 0W-40 right now because even the most expensive Amsoil (Series 2000) can't compare on spec. sheets to the Mobil 1. Either way you can't go wrong. I believe them both to be top-of-the-line lubricants that will help you see many many years from your beloved car.....

Or stick to Shell and use Rotella T synthetic 5W-40.

For more opinions and experiences, check this link-

http://www.oilanalysis.com/message_boards/by_category.asp?category=Car%20and%20Truck%20Lubrication