I'd go straight to a 15Kmile OCI. If your engine turns into a huge paperweight, back it off a couple thousand.

Sorry, I couldn't resist. All this paranoia about putting in synthetic oil that is light years ahead of the stuff available 25 years ago is totally unwarranted.

I'm still waiting for someone to convince me that 15kmile OCI, or for that matter 25kmile OCI with filter changes, has ever, and I mean EVER caused an engine related problem.

It's all smoke and mirrors folks.

240Joe