Or just go find some Brad Penn 10W-40. That's what a lot of us use and it's fine.
When you do the oil change you should address the oil filter, too. Look under the back end of the car for a spin-on filter. It could be any color but they are typically white, orange, blue or black and are roughly the size of a 4-cup measuring cup. If you have one, get another just like it at any NAPA or Autozone, etc. Mine is a spin-on and I use Napa Gold 1515 filters from a local NAPA auto parts store.
If you do not have a spin-on filter, then the engine has a simple screen filter inside at the bottom of the sump (crankcase). That's a bigger deal to change, requiring two sump paper gaskets like this:
https://www.cbperformance.com/product-p/1793.htm
The copper washers are important as they seal around the case studs against the sump plate which looks like this on the very bottom of the engine case:
https://www.cbperformance.com/...rdware-p/mstoscp.htm
Oil changes on these cars typically take an hour or so to do, depending on the filter needed. If you decide to have a mechanic do yours, then he/she will need the oil filter and/or sump plate gaskets (although NAPA parts stores sell them locally, too).