u/CPPPhenanthrene

I bought a 2001 CR-V and was advised by the previous owner that I should keep using a 15W-40 oil. He's been using it for a long time. I am skeptical about it since every CR-V's around here has been using 5W-30 (I'm living in a hot country).

When I changed my oil previously, I asked the mechanic to switch it to 5W-30. But I was advised that it is harmful and would emit white smoke if I will switch to a thinner oil.

I am getting mixed answers. Should I be worried for my car? Can I switch to 5W-30 safely?