The Best Type of Oil for a Lawn Mower

Choosing the right oil for your lawn mower engine is crucial to keep it running smoothly and efficiently for years to come. With so many types and weights of oil available, it can get confusing to pick the optimal one. This article will walk you through the key factors to consider and recommend the best oil for lawn mowers.

What Type of Oil Does My Lawn Mower Need?

Most push or self-propelled gas-powered lawn mowers require standard motor oil, typically with a viscosity grade of 10W-30. Here are the main oil specifications to check in your owner’s manual:

Oil Type

  • Conventional motor oil – Made from crude oil and commonly recommended for most small engines.
  • Synthetic blend – Mixed with around 30% synthetic oil and 70% conventional. Provides added protection.
  • Full synthetic – Made of synthetic compounds and resists breakdown. Best for high heat.

Oil Viscosity

  • Single grade – Based on one viscosity number like 10W or 30. Less stable in temperature changes.
  • Multi-grade – Has two numbers like 10W-30. Flows well in cold and maintains viscosity when hot.

Oil Rating

  • API – Minimum rating of SJ or SL is recommended. SH or SG may be required for some older mowers.
  • SAE – Viscosity grade will likely be 10W-30, 5W-30, or 10W-40.

Key Benefits of Using the Right Lawn Mower Oil

Choosing the proper oil improves performance and extends the engine life in the following ways:

  • Reduces friction and wear – Oil coats metal components to prevent direct contact and friction which causes damage over time.
  • Cooling capabilities – Carries heat away from engine parts to prevent overheating.
  • Cleans contaminants – Additives suspend debris so it can be flushed out during oil changes.
  • Prevents rust and corrosion – Forms protective coating on internal components vulnerable to rust from moisture.
  • Reduces noise – Allows the engine to run quieter and smoother.

Recommended Oil Types for Lawn Mowers

Here are the top oil options to consider for keeping your mower running optimally:

Conventional Motor Oil

  • Cost-effective – Budget-friendly option suitable for most mowers.
  • Common weights – 10W-30 is recommended for most mowers in all temperatures. 5W-30 can also be used.
  • Key brands – Valvoline, Castrol, Havoline, Quaker State. Look for SJ, SL or higher rating.

Synthetic Blend

  • Balanced performance – Offers some synthetic benefits without the full cost.
  • Improved stability – Resists thinning at high temps better than conventional oils.
  • Popular weights – 10W-30 and 5W-30 cover all weather conditions well.
  • Top choices – Mobil 1, Castrol GTX, Valvoline SynPower. Minimum SL rating.

Full Synthetic

  • Maximum protection – Best resistance to viscosity breakdown and oil sludge.
  • Superior in extreme heat – Better lubrication in hot running engines under heavy loads.
  • Preferred weights – 10W-30 or 5W-30 offer stability across temperatures.
  • Premium brands – Mobil 1, Royal Purple, Amsoil, Castrol EDGE. SL or SM ratings.

Lawn Mower Oil Change Best Practices

Follow these tips when changing oil:

  • Drain oil when engine is warm – Flows out quickly and removes sediment.
  • Change oil regularly – Follow mower manual but at least once a year.
  • Use the oil weight recommended – Don’t try thicker or thinner alternatives.
  • Check the dipstick – Fill to the full mark, don’t overfill.
  • Use clean containers – Prevents dirt and debris from getting in oil.
  • Recycle old oil – Don’t throw it in the trash, find a recycling center.

Frequently Asked Questions About Lawn Mower Oils

Can I use automotive oil in my lawn mower?

You can safely use certain automotive engine oils in your mower as long as they meet the correct specifications indicated in your mower’s owner’s manual. Make sure to use the proper viscosity grade as well, such as 10W-30 or 5W-30 motor oil.

How often should I change my lawn mower oil?

Most mower owner’s manuals recommend changing engine oil every 25 hours of use or at least once every year if not used that frequently. If operating under heavy loads, dusty conditions or high temperatures, change oil every 20-25 hours.

What weight oil is best for all temperatures?

A multi-grade viscosity oil like 10W-30 or 5W-30 allows good cold weather starting and maintains the right thickness when hot, so it’s suitable for use in all temperatures.

Can I use synthetic oil in an older lawn mower?

You can use full synthetic oils in most mowers, even older ones. Synthetics like Mobil 1 or Royal Purple are very stable and protect against wear, just avoid super thick weights like 20W-50 unless specified by your mower’s manual.

What oil rating do I need?

Most mowers require at minimum an API rating of SJ for conventional oils and SL for synthetic blends and full synthetics. Check for the latest API rating recommendation in your owner’s manual.


Choosing the best oil for your specific lawn mower model will keep the engine running smoothly for years of mowing. Use the owner’s manual recommendations for type, viscosity, and rating when selecting oil. Conventional motor oils work well for most mowers, while synthetic blends or full synthetics provide enhanced protection. Always change oil regularly under all conditions and recycle properly. With the right lawn mower oil, your engine will start easily, run quietly and allow you to maintain a beautiful yard for years to come.