It was used to be available at Shamsi Oil Trader. As per the shopkeeper Repsol is now filling locally, no more being imported in packing. For this reason he is now not stocking/selling as he doubts local filling for QC.
And I am not sure about other locations in Karachi.
If you ask me, I have found LM 10W-40 the best for my Sprinter. I have also tried 10W - 40 Repsol fully synthetic. I am not saying Repsol is second to LM. It is just that I feel my bike love LM more. I also observe better clutch and better economy with LM 10W-40 than any other brand/grade. To support my argument I have been using 10W-40 over 1.5 - 2 years now.