1998 Silverado ext cab, 5.7L with 165,000 miles. Never leaked a drop of oil until I bought my new Sierra. The next day I saw a 12" puddle on the driveway. Crawled under and quickly spotted the oil cooling lines all wet. Bought new ones, spent about 6 hours pulling fan shrowd, etc and replaced lines. Cleaned up all dirt n grime off of skid plates. Test drove, sat over night everything clean, sweet. Son drove truck next day about 15 miles round trip and parked on driveway. 24 hours later another 12" oil puddle on driveway. I crawled back under and the only place I see the slight evidence of a drip is at the front of the oil pan near front main seal.

Finally the quesiton, can a front seal leak out that much oil just sitting there or am I just missing something more obvious. Thoughts apreciated...yes I did check both ends of the recently replaced lines and they look fine. Oil on driveway was centered right below front main seal...

 

hay man sorry about your luck. To answer yes the front seal can leak some sitting there you may have a groove worn in the balancer shaft from the old 165,00 mile seal if that is the case you can buy a new balancer, or what they call a repair sleave that you can get at any decent parts store . Hay also you need to make sur the pcv system is working properly.And check the crank sensor in the timing cover the sensor has an o ring and that could be leeking too.hope this helps man good luck.