synthetic

I used fully synthetic oil on my 6k service. Just wondering if I can use semi synthetic oil on my next change or do I have to use fully synth every time once fully is used? Thanks. Sorry if this has been asked before but I couldn't find what I was looking for in search.

Hi guys I'm asking a question that has probably been asked many times before but as I am new to the forum and don't yet know my way round I thought I would pose the question to you good people. The question is which oil for the engine, I have read many different reviews on the internet with so...