Hi Scotty,
Should we use thinner (than recommended oil) during summer. Like it is going to touch 126 F (52 C) here in the Middle East?
For example, I have to use 5W-30 usally but my trusted mechanic (who is my student) told me to use thinner one like 5W-40 or 50 according to my engine performance.
Consult with your car user's manual. Some pf them have a chart showing the recommended oil viscosity based on the temperature.
The engine runs at 90C no matter the outside temperature. Use the viscosity in your owner's manual.
5w40 is THICKER than 5w30, not thinner. The higher the number, the thicker the oil (lower viscosity.) In older vehicles like mine, I use 10w40 in the summer (thicker) and 5w40 in the winter (thinner.) Newer vehicles should follow the owner's manual for the ambient temperature the vehicle is operating in.
