I know that BMW uses Castrol SLX nowdays for their engines. I'm going to change the engine oil and talked to one shop keeper and recommended me Castrol GTX. Castrol GTX is a bit cheaper than SLX and SLX isn't that usual in the shops and you have to go to directly to BMW which is even more expensive (17€/litre).
Is there a big difference between GTX and SLX in terms of engine tear for normal driving?
BMW 518g touring (e34) -96.