what OCI on 4.0L Jeep would be safe for this oil? I know many say this is not a 10k oil, and I would never go that long. But I was "thinking" about trying some of this oil next OC and was trying to justify the added costs by considering upping the OCI to 6k or even 7500 and use the larger FL1-A sized Ford filter to accomodate the longer OCI as well?