Yes, as long as they both meet manufacturer specs, no issues.
I will change my oil from conventional oil to synthetic oil on my next oil change.
Yes you can mix different brands but I recommend you do not mix different weights. You can even mix synthetic oil with conventional oil. But as the weight of the oil is critical, do not ever mix one weight of oil with another, no matter if it is synthetic or conventional oil.
All major brands of full synthetic are good.
If it is the synthetic blend, you should change the oil every 3,000 miles. If it is a full synthetic, you should change the oil every 5,000 miles.
Synthetic oil is synthetic oil. All brands are made from the same basic formula that has been around since World War 2. There is no real difference in any of the major brands. Buy the cheapest major brand. BTW, you will see no appreciable difference in mileage using synthetic versus conventional oil.
repsol fully synthetic
Mobil 1, Amsoil, Royal Purple, ......
Yes you can.
100% synthetic will not go bad by itself. What makes 100% synthetic oil bad is basic oil filtration. The oil filtration system on a car is not very efficient, therefore allows the oil to get dirty. Once the oil gets dirty, the oil does not fare as well. There are brands of 100% syn oil that only require a 1yr/25,000 mile change (with guarantees-- google search 25,000 mile oil change). There are others (on store shelves) that require a 5000 mile change, but charge the same price as the 25,000 mile oil change. Make sure to look for 100% syn. There are syn oils out there that are actually a "synthetic blend", which means it's part syn, part conventional oil.
Yes, you can even mix synthetic with conventional oil.
its the same process as changing synthetic oil, except you use regular 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.