My '09 Sentra 2.0 has had high silicone readings for it's whole life, and now it looks like wear metals are increasing, and oil isn't holding up as well during my 10k OCI's. Car has 110,000 miles, still runs and sounds great, but it must have a leak in the intake somewhere. I paid to have the spark plugs and PCV changed, so they had the intake boot off, but they didn't mention any tears. For now, I'm going to keep my intervals to 5k until I can figure what the issue is. I change the air filter every 25k, I always make sure it gets seated back in properly. Ideas??