I just bought a '97 Subaru Outback 2.5L with 248,000 miles (well serviced througout) and want to switch to synthetic oil. I have used Mobil 1 in my '96 Mercedes 220C since new and it runs the 0W-40. I notice Mobil 1 High Mileage oil is 5WX20 and was surprised. I expected it to be something more like 10WX40. Is the 5Wx20 too thin for the Subaru? If it's not the best choice, what should I use? Most driving will be highway miles.
Thanks
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