I use the Rotella full synthetic. It has quieted the rattle some. I got another 1+ MPG. It's cheap at the Wallies. And I read a report by a independant oil analyzing firm that said that is the best full synthetic on the market for the light duty diesel engine. That it beats the requirements by a long shot. I'd post the report but I have changed computers twice now since I saved it.
2004 Chevy K3500 CCLB DRW Duramax. Stock.
1992 Sea Ray 300DA. 30 plus foot Express Cruiser on a trailer. 13,500# boat and trailer and 69' of combined length rolling. Over length/width permitted load.
SOLD-95 GMC K2500 SLE 6.5L TD, Relocated PMD to bumper #9 res., Custom Lowes special induction tube, Triple gauges on the pillar EGT, Trans, Boost, High Idle Mod, TCC-Lock up Mod, Custom Back up camera, DIY Manual Wastegate Controller, 4" from down tube to 5" stacks, Vac Pump Removed,2007 wheels, WMI by Cooling Mist 8gph @3psi 11gph on demand