Havoline Synthetic is just as good as any other synthetic.
Semi synthetic or synthetic blend is a combination of synthetic and conventional oil. Full synthetic oil is just that 100% synthetic oil.
Yes, Synthetic oil is synthetic oil no matter who makes it.
No an oil filter just filters the oil no matter synthetic or not
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.
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.
The GM book did not say anything about the type, just that it was 75W90 synthetic. So just by a good name brand. Gastrol is a good brand.
yes,of course.
Synthetic. Turbos should always be synthetic.
Yes, without any issues. That's what synthetic blend oils are (better than conventional oil, not quite as good as pure synthetic).
All major brands of full synthetic are good.
You can mix part synthetic oil with full synthetic oil.
Not necessarily. The w just means it is a winter oil as in SAE 5w20. It is 5 weight when it is cold and 20 weight when it is at full operating temperature. It can be conventional or synthetic. The can will say Synthetic or Synthetic Blend if it is Synthetic.