Originally posted by HarryM
Synthetic oil is about 4 times the price of mineral oil. For that price it has to be 4 times better, but is it? If you use mineral oil and change it twice as often, you're still money ahead. I'm voting for Castrol 10W40.
Here's my experience with Mobil 1, various weights in gas engines:
1981 Chev. Citation 2.8l V6
Owned from 1984-1994, put 120k miles total on the car, averaging 12k/miles year. I changed the oil 10 times (with filter), because 12mo./25k miles is what Mobil recommended in the early years. Car was donated to a race project, it never had any problem involving a lubricated part.
1989 Ford Probe GT
Currently owned, owned since 1989. There are 155k miles on the car, using Mobil 1 for 145k miles. The oil has been changed (with filter), on average, every 8 months. There has never been a problem with any lubricated part, including the turbo. I take no special precautions for the turbo at shutdown.
Neither of these cars have had special care and are/were often started under below freezing conditions.
I am a synethetic oil believer. I also use synthetic in my MB. For me the price of the oil is inconsequential. I like to change my own oil, but I don't want to do it very often.
This is not an argument against using conventional oil, rather it is my successful experience with synthetic.