Not the snobby or PC answer, and probably not even the *right* answer in this case, but perhaps food for thought. With 172k miles, have you considered going to a high mileage oil to see what happens? Not sure if this is your only vehicle, but if it isn't it might be worth a shot. The other seals could probably use it regardless. How bad are the VC's leaking? When it comes to Flat engines like these, the least intrusive method is most often the correct answer for me. I have no time for BS since I own several other cars that also give me trouble.