The first thing you should always have in mind at the time of choosing a motor oil is to choose one which respects the indications from your car owner’s manual. You should not use motor oil different than the one indicated in the car’s manual since it could damage the car.
Most newer cars can use a wide range of motor oils which reach certain standard. This way, once you have learnt what motor oil the car owner’s manual indicates, you might be able to choose among a range of oils which fulfill those indications and enter into the description.
One of the aspects in which certain motor oil might vary from another is viscosity. Lighter oils help improving fuel oil economy as well as they circulate more quickly, reaching faster upper areas when the car is first started and the engine is cold. This is important since one of the main factors which cause engine wear is the difficulties it goes through when it starts while being cold, and therefore using an oil which can be helpful in this is very important.
A good oil choice for new cars would be a multiviscosity 5W-30 oil which is very light and convenient for every day regular driving. If your car engine is not so new, then a 10W-30 would be a good oil choice. Also, if you usually drive your car in a hot weather and at a high speed, then a 10W-30 or a 10W-40 would be a good oil to use.
If you drive in cold weather you should avoid heavy multiviscosity oils. Heavier multiviscosity oils would need hot to run easily and it could be an obstacle for the engine start and its general functioning if it is used in a cold weather. If you use 30W or40W oils, you should have in mind that, although they are good for hot weathers, these kinds of oils could become an obstacle at the time of starting cold engines in cold weathers. Therefore, if you use 30W or 40W oils and weather becomes cold you should change to a straight 20W oil which would circulate easily even though the engine is cold.