What is the best of the best as far as extended drain oils are concerned? I am running a 12,500 mile/6 month oci on my wifes truck right now with Mobil 1 Extended Performance 5w30 and Mobil filter and I am thinking about switching over to AMSOIL Signature Series 0w30 and EAO filter next change. Is there any better oils than AMSOIL Signature Series for long OCI's? I don't care about price, what I do care about is crawling under that truck more than I have too. I would really like to find a 1 year 25,000 oil...Amsoil claims that, however has anyone ever done it with UOA to prove it could go that distance?
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