: This oil helps remove existing sludge and prevent new buildup in older engines. It is a favorite among mechanics for extending the life of high-mileage passenger cars and light trucks. Available at Walmart for $27.97 $24.97.

Mobil Delvac 1300 Super Heavy Duty Premium Synthetic Blend Diesel Engine Oil 15w-40 Go to product viewer dialog for this item.

These oils are built for the extreme stress of diesel engines in trucks, agriculture, and construction equipment. Shell Rotella T6 Full Synthetic 15W-40 Diesel Engine Oil Go to product viewer dialog for this item.

: Expertly engineered to withstand the intense pressure of modern engines, this oil uses "Fluid TITANIUM Technology" to reduce friction. It claims to provide 10X better high-temperature performance than industry standards. You can find it at Walmart for approximately $27.48. Pennzoil Ultra Platinum 5W-30 Full Synthetic Motor Oil Go to product viewer dialog for this item.

: This is a leading choice for diesel pickup trucks and heavy-duty fleets. It features "Triple Protection Plus" technology to protect against wear and deposits in extreme climates. It is available at AutoZone for $34.99 $25.99.