10w30 Synthetic oil is what is best for any air cooled engine. You can also use straight 30w.
sae30
SAE-30
Briggs and stratton engines use different oils depending on the temperature to which the engines will be used. Generally sae30 oil should be used for mower engines
Briggs Stratton makes many different lawn mower parts. On their website one can find standby and portable generators, pressure washers, cleaning systems and snow blowers.
Generally Briggs calls for 30W but you can also use 10w30 especially if you are using it in cool temperatures.
SAE 30 weight full synthetic oil.
regular 30 W, it says elsewhere on the Net, at least for some models in your category
Without knowing what engine or what kind of mower it is this is just a guess. But, it is possible that your flywheel and/or coil have gotten rusty and are not getting the conact that they need to make the spark. Try removing the cover and sanding the flywheel and coil. If it is a riding mower with a key switch there are many possibilities including anything from a bad switch to one of the safety switches.
SAE 30W in the summer and SAE 10w30 in the winter. I recommend you use 100% synthetic oil in any air cooled engine.
straight 30 or a 10w30
10w - 30
SAE 30 weight or SAE 10W-30 weight. I recommend you use 100% synthetic oil in your air-cooled engine.