There are different Delo 400 products but Delo 400 Multigrade 15w 40 is NOT semi synthetic. It makes no mention of it anywhere other than to say it is formulated using ISOSYN technology or something to that effect. Purely marketing....
There is a product called Delo 400 XLE Synthetic and yes, that particular one is fully synthetic. Another is Delo 400 XLE Synblend and therefore semi synthetic. But we are talking specifically the 15w 40 Multigrade product with the green writing I thought.....
Quote 'ISOSYN Advanced Technology, a combination of Chevron’s formulation expertise, high performance additive chemistry and premium base oils'
https://www.caltex.com.au/-/media/d...ces/caltex-lubricants-product-guide-2016.ashx
Happy to see evidence of information otherwise but hope this clears this up
Damo