Small Engine Oil Types Explained: SAE 30 vs 10W-30 vs Synthetic

Walk into any auto parts store and you'll see dozens of oil options. For small engines, the choice is simpler — but picking the right one matters.

SAE 30 is the traditional choice for small engines and what most manufacturers have recommended for decades. It's a single-weight oil designed for warm weather operation (above 40°F). It's affordable, widely available, and works well for most lawn mowing conditions. If you only mow in summer, SAE 30 is a solid choice.

10W-30 is a multi-weight oil that performs well across a wider temperature range. The '10W' means it flows like a 10-weight oil when cold, and the '30' means it protects like a 30-weight oil when hot. This makes it a good choice if you use your equipment in spring and fall when mornings are cool. Most modern small engines now list 10W-30 as an acceptable option.

5W-30 is used by some newer engines — particularly Honda — and provides even better cold-weather flow. Only use this if your manufacturer specifically recommends it.

Synthetic oil (typically 5W-30 or 10W-30 synthetic) provides superior protection across all temperatures. It resists breakdown better than conventional oil, flows better in cold starts, and handles heat better during extended use. It costs more — roughly double — but many professionals consider it worth it, especially in expensive riding mower engines.

What about mixing? Don't mix different oil types or weights. When changing oil, drain the old oil completely before adding new. And always check the dipstick after filling — small engines don't hold much oil, and overfilling causes its own set of problems.

Our recommendation? Use whatever your engine manufacturer recommends in the owner's manual. If you've lost the manual, SAE 30 or 10W-30 conventional is a safe bet for most Briggs & Stratton, Kohler, and Kawasaki engines. When in doubt, ask us — we'll tell you exactly what your engine needs.