I was going to leave it stock...

5w/40w shell rotella t6 synthetic
zinc levels are good/good price
use it for everything ! buy it by the 5gal pails !!!
PRODUCT DETAILS
Part No. 550019886



Shell Rotella® T6 5W-40 Diesel Engine Oil is a full synthetic motor oil that features exclusive Triple Protection Plus technology, formulated with fully synthetic base oils plus advanced additives to protect against wear, deposits and oil breakdown PLUS better low temperature flow and increased fuel economy performance, without compromising durability, compared to conventional SAE 15W-40 oils.

Product Features:

• Provides 1.5% improved fuel economy performance compared to SAE 15W-40 oils
• Triple Protection Plus formula combines fully synthetic base oils with advanced additives for excellent equipment protection and long engine life
• Formulated with additive technology that protects against the effects of soot, dirt and other contaminants
• Engineered with shear stability to resist viscosity loss and maintain optimal engine oil pressure
• Suitable for diesel-powered vehicles from tractor/trailers to classic cars and heavy-duty diesel pickups that allow an SAE 5W-40
• Specifications, Approvals and Recommendations: API: CK-4, CJ-4, CI-4 PLUS, CI-4, CH-4; ACEA E9; Allison TES 439; Caterpillar ECF-2/ECF-3; Cummins CES 20086; 20081; Detroit Fluid Specification (DFS) 93K222, 93K218; Ford WSS-M2C171-F1; JASO DH-2; JASO MA/MA

they even mention classic cars now !!