Oil and fluids covers the lubricants and working fluids that keep vehicles and machinery running: engine oils, antifreeze and coolants, brake fluid, transmission and hydraulic oils, greases and fuel system cleaners. Start with the vehicle handbook.
Engine oil
Engine oil is chosen by viscosity and specification. The viscosity grade follows SAE J300: in a grade such as 5W-30, the number before the W (for winter) describes how the oil behaves when cold, and the second number its thickness at running temperature. The specification shows what the oil is approved for. ACEA A and B categories cover petrol and light diesel engines, and C categories are lower-ash oils for engines with exhaust after-treatment such as diesel or petrol particulate filters. Many vehicle makers also set their own approvals, so match both the grade and the specification in the handbook.
Brake fluid and coolant
- Brake fluid: DOT 3, DOT 4 and DOT 5.1 are glycol-based and absorb moisture over time, so keep to the vehicle maker's change interval. DOT 5 is silicone-based and must never be mixed with the others. Use the type the vehicle maker specifies.
- Antifreeze and coolant: use the coolant type the vehicle maker specifies, and check whether the product is a concentrate to be diluted with water or ready to use.
- Other fluids: transmission and hydraulic fluids each have their own specifications and grades, so match them to the vehicle handbook or the equipment maker's instructions.
Safety and disposal
Oils, coolants and brake fluids are chemical products, so follow the manufacturer's instructions and safety data for handling and storage. Take used engine oil to a waste oil bank so it can be disposed of responsibly.
For tools and repair products, see repair and maintenance; for washing and polishing, see cleaning and polishing.
