Castrol GTX

I tried to buy my usual Motoquip engine oil for my next upcoming oil change, but my local retailer is no longer stocking it. I was offered some German stuff for an astronomical price which I declined. On the way back I stopped at a petrol station to top up on diesel and noticed they had Castrol GTX engine oil on the shelf for a very much more reasonable price (still a total rip-off, but less than half the price of the German fully synthetic stuff.)
Is there any reason why I shouldn't use GTX in my TD5 engine? On the label it claims to be suitable for both petrol and diesel engines so that should be good enough, right?

Castrol GTX its been about a long time even in my days when I was using Duckhams Q.
GTX was a mineral oil maybe still is, oils have move on a bit now being part or full synth but if GTX meets the LRs oil spec for your engine use it why wouldn't u, Castrol is one of the top brands.

TD5 is intended to have fully synth, but I routinely use a good semi synth and it's fine at 220000.... I'd guess fully mineral may have less durability, and a bit more internal resistance due to viscosity, and prob not so suited to really adverse conditions, but with regular changes don't see it being an issue? Cheers, A

Tesco fully synthetic is about the cheapest I could find