Schaeffer Manufacturing Co SynShield OTR Plus 5W-40 Full Synthetic Diesel Oil, 1 gal x6, API CK-4, DPF-Safe

This advanced synthetic-plus formulation combines thermal stability, detergent action, and proprietary friction modifiers to help control wear, soot, and deposits in contemporary diesel powerplants. It meets API CK-4 performance guidelines and is designed for use in 2007–2010 emission-compliant engines that rely on heavy EGR and after-treatment systems such as DPFs, DOCs, and SCR units. Packaged as 1-gallon bottles sold in a pack of six, this oil targets commercial and industrial users who need dependable lubrication under demanding conditions.

How does this 5W-40 oil protect engines under heavy-duty use?

Schaeffer’s SynShield OTR Plus uses a blend of antioxidants, detergents, and shear-resistant base stocks to maintain film strength at high operating temperatures. The formula minimizes metal-to-metal contact and resists viscosity breakdown so moving parts remain protected during long runs and heavy loads.

• Full synthetic base stocks for thermal and oxidative stability
• Friction modifiers (Micron Moly and Penetro) to reduce wear
• High-temperature oil strength that resists thinning

Will this oil work with exhaust after-treatment systems like DPFs and SCR?

Yes—SynShield OTR Plus 5W-40 is formulated for engines with EGR and common after-treatment devices. It balances soot control with dispersancy to help keep filters and catalysts functioning as intended without contributing excessive ash or deposits.

• Compatible with diesel particulate filters (DPFs) and diesel oxidation catalysts (DOCs)
• Designed for engines using selective catalytic reduction (SCR)
• Good soot-handling and deposit-dispersing properties

How does this oil perform in cold starts and fuel-efficiency terms?

The 5W cold-grade rating gives improved flow at low temperatures for easier starts and faster oil circulation, while the friction modifiers and low-wear chemistry support smoother operation that can help maintain fuel economy. This balance helps equipment start reliably in cold conditions without sacrificing in-service durability.

• Superior cold startability for quicker oil flow on startup
• Friction reduction for smoother operation and sustained fuel economy
• Keep-clean additives that minimize deposits that can reduce efficiency

What service specs and equipment is this oil intended for?

SynShield OTR Plus meets API CK-4 performance levels and is appropriate for a wide range of heavy-duty diesel engines built to newer emissions standards. It’s suitable for fleets and individual equipment owners running on-road or off-road diesel engines requiring CK-4 lubrication.

• Meets API CK-4 specification for modern diesel engines
• Recommended for 2007–2010 emission-compliant engines and newer
• Appropriate for on-highway and off-highway heavy-duty applications

Who is this for? Schaeffer SynShield OTR Plus 5W-40 is aimed at fleet managers, heavy equipment operators, and technicians who demand a high-performance full synthetic diesel oil that balances protection, deposit control, and fuel economy. It’s a practical choice for vehicles and machines that operate in varied climates, face heavy soot loads from EGR systems, and require oil that supports modern after-treatment systems. Choose the pack-of-six 1-gallon set for convenient stocking and regular service intervals in garages, service trucks, and maintenance shops.