Another classic example is 10W-40. This one is a bit thicker in the cold (the 10W) and much thicker when hot (the 40). Think of it as the oil for an older truck that leaks like a sieve—the thicker oil stays put.
It’s also great for high-mileage engines that have worn parts. The extra thickness fills in tiny gaps, like using caulk on a leaky window. Not exactly poetic, but your engine will thank you.
If you used a 10W-40 in a snowstorm in Minnesota, it might be a little sluggish. Your engine would crank slower, like you trying to run in a pool of cold honey. That’s why you check your owner’s manual for the specific rating.
Steering Toward Full Vehicle Autonomy - Mobility Engineering Technology