You can but I would not advise it. Use only 10w30 or straight 30 weight. I also highly recommend using Synthetic in an air cooled engine.
5w30
5w30
yes yes
5w30
Use 5W30.
5W30
5w30
No, not if the recommended weight is 5w30. Only use the weight recommended by the manufacture.
5w305w30
A good brand of 5w30
sae 5w30
5w30