Quote from an Isuzu tech:

"the piston has three rings top compression second compression and oil scraper ring the oil scraper ring land (groove) has oil drain back hole in the piston which get plugged causing oil consumption I've reringed to many of these motors under warranty for isuzu."



The Isuzu service bulletin regarding excessive oil consumption (> 1qt per
1000 miles) is service bulletin # IB00-01-5002.
As for Oil useage, I was reading my CD manual last night, and it stated the following reasons for increased oil consumption: 1. Dirty EGR (system) 2. Dirty PCV 3. Carbon up piston rings 4. Long highway trip 5. Towing