motor oil...is there an expiry?

[chister]

I need to do an oil change and would like to put synthetic oil in the GS. I have 2 liters of Castrol synthetic, they are unopened but about 10 years old.
Does anyone know if the age of unused old is an issue towards its effectiveness?
Is it ok to mix old Castrol synthetic with new Castrol synthetic?

[EdChen]

I'm sure a good deal has changed in the last ten years.   I think the shelf life really depends on the environment you kept it is, temperature changes, moisture.  I would think that it is safe to say that the 10 year old oil is past its shelf life.    this website: http://www.carbibles.com/engineoil_bible.html says that engine oil has a shelf life of abou 3 years.

I'd personally jsut go for new oil.