Semi synthetic motor oil?

[nashvillecat]

Over the years I have used well known brands of synthetic oils and typical mineral oils (e.g., Valvoline/Kendall/Shell/Agip 20w-50) in my e-9/e-3's. Since I change my oil 2-3 times a year depending on my mood, I probably do not benefit much from synthetic oils. I do use it on newer cars that have come so equipped. For some reason, I never paid much attention to semi-synthetics and even wondered if I couldn't blend my own. But each time I think about it, I can't really understand the wisdom of semi oils to begin with.

Castrol says it is a cost-effective middle ground, what ever that means http://www.castrol.com/castrol/genericarticle.do?categoryId=8264018&contentId=6003233

Does anyone here use semi-synthetic motor oil? Why? and do you recommend others (like me) follow suit?

Thank you.