Synthetic motor oils are fuel efficient, extended life lubricants manufactured from select base stocks and special purpose additives. Synthetic oils once had a bad reputation for leaking because the seal-swell properties s of the new synthetics were different from those of the mineral oils they replaced. This situation has gotten better, as you should no longer have a problem going back and forth between the two, but the risk is still there.

On the Other: Mineral Oil

Some people are not believers in synthetic oil. Mineral oil is one of a number of inexpensive byproducts that are made from petroleum. However mineral oil has absolutely no nutritional value, and it is a known carcinogen. It is used for cosmetics and personal hygiene products and motor oils. Based on these facts, synthetic oil seems to be the best bet for your lawn mower.

Bottom Line

Ever since the invention of motor oils, manufacturers of synthetic oils have tried to teach the public about the truths and falsehoods of synthetics. The necessity for consumers to make their oil purchase decisions based on quality rather than price is the most important thing.Based on the facts about both synthetic and mineral oils, it seems synthetic motor oils are the best for a lawn mower.

Source:

The benefits of using synthetic oil in your lawn mowers. | Lawn Care Business Marketing Tips - GopherHaul Blog

Synthetic Oil - Facts and Myths - Amsoil

Motor Oil: Synthetic vs. Non-Synthetic - Popular Mechanics