Havoline Synthetic is just as good as any other synthetic.
Yes, Synthetic oil is synthetic oil no matter who makes it.
Some cars as well as aircrafts use synthetic oil. Whether you should use it in your car or not will depend on the age of the car as well as its milage. If its too old, its probably not a good idea.
Several companies make a motor oil specifically for high mileage cars. Also a good synthetic oil might be just as good.
Usually they use synthetic race oil
Yes, your 50% off coupon is good for an oil change using synthetic oil. The coupon is good for an oil change using any oil of your choosing.
Ful synthetic oil is the best oil to use, it wont hurt your car with 20 miles or 200,000 miles.
Around 5,000 miles with conventional oil and 7,500 with synthetic.
You can use it in all cars
Synthetic oil is needed in a vast majority of high-performance machines (especially turbos) because of the risk of engine sludge.
You need to think about what you are going to be using it for. Also, whether the oil is synthetic or not. Buying good oil is very important. Synthetic oil is not always good.
Synthetic works really well but is more expensive. Also, if you start using synthetic oil, you need to continue to use it and avoid mixing the two types of oil. If you are not sure you could keep on with the synthetic, then use traditional. In any case, get your oil changed regularly.