There are several full synthetic oils that have long drain intervals. I’ve been using Amsoil since the mid 70s and have had several vehicles in which I employed that type of drain interval..but always using oil analysis in conjunction with it
I use Amsoil on the Ascent, but stick to the guidelines by using a little lesser product. The fact that so many here have reported increasing oil levels (me included) says there is likely some fuel dilution occurring? My anecdotal thought is that’s the reason for the shorter drain period.
And.. I think if the book says 6K mile oil change, then it needs to be changed then to concur with Subaru law
