You asked if anyone uses Amsoil in their cars. --- Sorry I have only used Mobil1 0-40. Since I have a lifetime warranty on the drivetrain I only use approved oil. I do not think Amsoil is approved by Mercedes standard (229.5). I am NOT saying Amsoil is bad I am only saying it is not approved for my warranty.

Since I drive only about 2000 to 3000 miles a year during the spring, summer and fall. I change the oil once a year. I do this just before their winter nap. I change all fluids based on time rather then mileage. I change air filters based need. I use the date the car was placed in service for all time changed items. When I purchased used Xfires I changed everything and then started the time from then. I also changed out the brakes and rotors. I hated the dust every time I drove the car.

First IMHO it is most important is to change the oil and filter before it's winter nap. Second, I change the brake fluid before their nap.

If you don't know the date in service just call a Chrysler dealer and give them your VIN and they will tell you that date.