I have a "fresh" rebuild in my van (not a w/boxer, but that doesn't matter) and the builder demands I run their specific brand of oil at least 5000 miles, and would prefer I leave it in for 10,000, which I am doing. I'm changing it every 2500-3000 miles, using the same break-in dino oil they require, with fresh filters.

I'll switch to Syn when I get 10,000 on it.

Bob
'87 Syncro Westy Subie 2.2