It's worth reading this:
http://www.350z-uk.c...r-mineral-oils/
To a lesser degree, the points covered in the above would apply to semi- synthetics also.
The other point is that when it is not clear what use the car is going to be to, it pays for members to be cautious with oil recommendations.
Extract from a European Court judgement: "Synthetic is a marketing term and its up to the marketer of the oil to define what synthetic is." Therefor, any oil that is subjected to any unconventional practice can be labelled synthetic.Most "fully synthetic"oils have as much as 20% petroleum product added as a carrier oil for the additives, so it is labelled as "fully synthetic" when it is not. Why,if "fully synthetic" is so good,are the change intervals exactly the same as mineral oils? It seemed to me that some of the answers given to Justin may have scared him into thinking it would wreck his engine, when,as Jezz said, it won't do any harm at all. Regards, Keith