Recommended Oil Types SAE 30: Best for consistent warm weather (above 40°F / 4°C). 10W‑30: Good for varying climates; easier cold starts but may consume more oil in hot weather. Synthetic 5W‑30: Works across all temperatures, improves cold‑weather starting, and reduces oil consumption. Avoid automotive oils with friction modifiers — they can damage splash‑lubricated mower engines.