I have a 14 Subaru FB25. In the owners manual it states 7500 OCI. In the 15 Forester manual, it states the OCI is 6000 miles. So, what to do? I am using Pennzoil Platinum for the foreseeable future in it and my Honda. Thanks to the Shell gas deal, at have 250 quarts of it. I plan on getting a UOA after a 5k run on the PP. What would you do? 6k or 7.5k OCI?