You should use the oil weight recommended by your owners manual. For cars that burn or are otherwise likely to be low on oil at some point, synthetic oils have superior lubrication and thermal resistance properties especially useful in high performance or high mileage vehicles. You should however investigate the cause of burning oil.
It is better for engines, more pure and burns cleaner. It's better for care engines.
Heavier oil will move slower and maintain higher oil pressure. The heavier oil will be slower to get past the piston rings and the valve stem seals, resulting in less oil burning. Heavier oil is generally better for worn engines, but if the engine isn't worn, you should use the thinner grades of oil, as originally recommended.
Multi viscosity if you are in a colder clime, if not straight 30. It's better to go with a heavier oil on older engines for better sealing.
yes it can be substituted, you might want to use a little LESS of the olive oil, as it is heavier and has a stronger taste.
You can try going to a little heavier oil but it will unlikely help much with the oil burning. A high mileage oil would be a good choice.
Just the opposite, 30 weight oil is thinner that 40 weight oil and will flow better at low temperatures.
Water is heavier.
The suggested motor oil for a 1997 Mitsubishi Galant is a light 5W30 conventional oil. Older engines made need a little heavier oil to prevent leaking.
How many miles on vehicle--internals may be worn Rings, valve seals/guides etc. What weight oil are you using--may be able to go to a heavier weight
All Kia products are designed to be operated with 5w-20. In an emergency you can add a different oil weight to get you by, but use as little as possible for as short a time as possible. Change the oil and filter as soon as you can and replace oil with 5w. The heavier oil will not hurt your car, HOWEVER, the tolerances on these engines are so exact that running a heavier oil in your car will actually expand the area between the lubricated parts. What does this mean to you? Extended use of the heavier oil will cause oil loss and smoking as the lighter 5w oil leaks into the cylinder and is burned at combustion.
oil
No water is heavier then oil.