1998 ford explorer oil change?

[Jazzy]

So I bought a truck for the winter and need to put some work into it first,
It has over 196000 miles on it
The previous owner never took it to a mechanic so I already know what I got myself into
What oil would you recommend I use?
Synthetic or no synthetic? It currently does not have synthetic
What is your opinion

 

[HarleyDrive]

20-50 regular or 10-60 synthetic unless it's a diesel then just 10-60 synthetic