"Murriel" wrote:
Years ago I was told not to use automotive oil in garden tractors and
lawn mowers but rather oil especially formulated for those devices,
such as brands bearing the names "Briggs and Stratton," "Cub Cadet,"
etc.

Who the heck told you that? The dealer of the shop that wanted to sell you
that four dollar quart of oil?

Both Briggs and Tecumseh recommend the use of standard SAE 30 weight
detergent motor oil to be used in their engines. The only exception is Tec,
who recommends SAE 10w30 weight detergent motor oil for use in cold
temperatures.

Buy SAE 30 weight detergent oil. Change it once a year, when you sharpen
your blade. Always use fresh gas, and run it out at the end of the season.
Oh, and clean under the deck after each mow, and let it dry.

Jon