Look in the owners handbook, you can use a range of oils (5w-30, 10w-40, fully-synthetic, semi-synthetic etc)
Thanks Kam05. Yes, I did read this spec from the Owner's Handbook. But in terms of the Castrol Edge oils Castrol advise the use of 0W-30 for the IS200. I think I read somewhere that going to fully synthetic can mean a slight change in the grade - I wonder if this might be the reason. If I were to use Castrol Edge, any comments on using 0W-30, as advised by Castrol, rather than, say 5W-30?