Purpose and Specifications

CASTROL 15518E is a heavy-duty transmission lubricant designed for manual and automated manual transmissions in commercial vehicles and trucks. This mineral oil-based fluid with a viscosity grade of 75W-140 meets API GL-5 specifications, making it suitable for high-load gear systems that demand superior protection under extreme pressure and temperature conditions.

The 75W-140 viscosity means the oil flows easily in cold conditions (down to approximately -40°C) while maintaining a protective film at high operating temperatures (up to around 100°C and beyond). This dual-temperature performance ensures reliable lubrication whether your vehicle operates in winter or summer climates.

Key Benefits:

• Excellent load-carrying ability for gears under heavy stress
• Outstanding wear protection for transmission components
• Superior oxidation stability to resist breakdown during extended use
• Anti-rust and anti-corrosion properties to protect internal metal surfaces
• Anti-foam additives to maintain consistent hydraulic performance

When to Use / Replace?

CASTROL 15518E is recommended for commercial trucks, heavy-duty vehicles, and equipment with manual or automated transmissions requiring GL-5 specification fluids. Check your vehicle manufacturer's manual for the exact fluid requirement—using the correct specification is critical for transmission longevity.

Replacement Schedule: Most commercial vehicles require transmission fluid changes every 50,000 to 100,000 kilometers or 12 to 24 months, depending on driving conditions and manufacturer recommendations. Severe-duty applications (frequent towing, mountainous terrain, stop-and-go traffic) may require more frequent changes. Always consult your vehicle's service manual for precise intervals.

Storage: Store in a cool, dry location away from direct sunlight. Shelf life is typically 3 to 5 years when properly sealed and stored.

Frequently Asked Questions

Q: Can I use this in my passenger car transmission?
A: No. CASTROL 15518E is formulated for heavy-duty commercial vehicles and trucks. Passenger cars require different ATF specifications (like DEXRON or MERCON). Always follow your vehicle manufacturer's recommendation found in your owner's manual.

Q: What does 75W-140 mean in practical terms?
A: The 75W rating means it flows smoothly in cold weather (winter starts are easier). The 140 rating means it stays thick and protective at high temperatures during heavy work. This combination is ideal for trucks that work hard in varying climates.

Q: Is this mineral or synthetic oil?
A: This is a mineral oil-based transmission fluid. Mineral oils are cost-effective and suitable for standard commercial applications. Synthetic alternatives may offer extended drain intervals but at higher cost.