I think that everyone has their own idea but let me add my 2 cents worth. If the manufacturer states 10w30, then use it. I've been using Castrol GTX High Mileage for years with no problems. I substitute a quart with Marvel Mystery Oil (its been around for a long long time), change the filter and add ZDDP. For about the last 10 years I've used a filter magnet-it attaches to the filter and traps microscopic metal from moving around the engine. It's called Filter Mag. Just go online and read about it. Good luck!