you may get slightly worse gas mileage, and if your car is under warranty it may void it. but it wont hurt the engine, just switch back to 5w-20 when you can.
Your engine will seize and you'll have to buy a new car
And why in the world would you do that? They both cost the same amount. You may void the manufactures warranty. Do not use any other weight than the weight recommended by the manufacture of your vehicle.
If it's zero degrees F or less you should use 5w20. Otherwise it might leak out faster and your valves might tap at start up. remember; very hot outside or old car use thicker oil 10w30 or 10w 40, very cold out side or brand new car use thinner oil 5w20 or 5w30. for the best lubrication use the thinnest oil you can, but the thinner the oil the faster it will breakdown in extreme heat
You will have excess engine wear. Look at it this way. The engineers designed the engine in your car. They then chose a weight of oil that you should use. You decide to ignore them and use something else. What exactly do you think will happen? And besides, what good reason do you have for using a weight of oil other than what they recommend? But, it is your car so use what you want, just don't expect good results.
When the vehicle manufacturer recommends it.
If your car doesnt require it I would stick with the 5w30 rather than spending more on 5w20
Yes, no problem.
It could be.
What year is this car? I suggest using Pennzoil 10w30.
Allways use the recomended oil in your car. Depending on year and model (not provided) 5W20 MAY be correct.
To keep an engine running well, a person must use the appropriate fluid type in their car. A 1999 Mazda 626 takes 10W30 engine oil.
The loan company takes the car. You loose it unless you make up the missing payments and pay the fees.