Newbie Question on OIL CHANGES

[Rodger Wilco]

I know that this question has probably been asked but I cant find it so here goes:

I just bought a used 2010 Yaris with 17,000 miles on it. I have driven it less than 200 miles when the "oil light" started flashing. I have no idea what to buy.

Should I go SYNTHETIC or CONVECTIONAL, or BLEND?

What type of FILTER?

The owners manual merely says 5W-30 and make sure it is API SM...

...Well that gives me a lot of choices.

The previous owner used Mobil 1. I read that if you change oil types it will cause some of the seals to leak.

Is the synthetic thing a waste of money or a good investment? And what about the filter?

What are you guys using and why?

Thanks in advance.