2002 SILVERADO 4.3 ext cab V6 143,000 Miles - Using PENZOIL Blended Synthetic from Jiffy Lube * Previous Owner Die Hard Mobil1 I've been wanting to start modding my truck! but I can't until this issue is fixed... or I know more about it. In fact I am going to stop going to Jiffy Lube places and start changing the oil myself. The previous of owner was a hardcore Mobil1 Full Synthetic fan. I bought it switched to PenZoil 5-30 Blended Synthetic. I bought the truck with 137K, changed the oil to PenZoil a few days after. Some from 137k to 141k I had a front seal leak, I fixed it. So after changing at 141k, I had a Check Engine Oil level light come on, oil was low, topped off, this was at 143k. I do notice some oil resdue/stains at the rear main seal.. but it looks small. There is no smoke either. In fact after cleaning engine and underneath I drove her around like crazy for two days and didn't notice much. I love my truck, even if it's a V6 it's [censored], I come from a Ford V8 loving family. I gotta get this issue fixed. This is the first truck I bought on my own, and want to keep her going through my college years. SO, Is it the oil? A friend of mine told me that Penzzoil once did this to them and too switch back to Mobil-1? I've heard if you use PenzOil Ultra/Plat it cleans the engine and stops oil burning. But.. I've also heard that Mobil 1 HIGH MILAGE Full Synthetic is a lot better and will prevent leaks... If I should siwtch Oils, should I use Penzoil Ultra/Plat *dexos approved or MOBIL 1 HIGH MILIAGE FULL SYNTHEITC * which doesn't have the dexos logo. Please help me out here, this is killing me.