Side mirrors stopped working and help choosing grade of engine oil

Hello, I recently bought a used 2013 Santa Fe with the 2.2L turbo diesel engine with an automatic transmission that is pretty low mileage (~87k miles/~139k km) for it's age from a guy that took care of it overall. It's really comfortable in heavy traffic and it's been great so far for the few days I been driving it. The truck had a few cosmetic defects but it isn't serious considering I bought it for a really good deal. The only issue I'm trying to address atm are the side mirrors that don't work, what would I need to check to get them working again?

On another note, I live in a hot tropical climate (Nicaragua), so what grade of engine oil would be recommended? I know I'll have to purchase oil for diesel engines so out of the two, which do I get? 5W-30 or 5W-40? Is there a certain brand that is the best such as Shell Rotella engine oil used by semi trucks and such for example? The engine runs great, doesn't leak and since it has less than 90k miles, it shouldn't be considered a high mileage vehicle. What is the recommended mileage I should change the oil, oil filter and such? I'll be purchasing full synthetic engine oil too.

I'm asking these things because my Santa Fe didn't come with a manual and answers seem all over the place when looking for information on what grade of engine oil to use in a hot tropical climate.