I highly value the recommendation from jz, capsat and rizkhna. Why? Cuz they've pointed you in the right direction. Just to add the cherry toppings.......Engine flush is perfectly fine with this model (provided you wanna do it for satisfaction sake). Show some patience while draining the oil, wait until the very last drop makes its way out. Use Mobil 1 (Authentic), or any other fully synthetic oil of the correct grading. Do not compromise on the quality of oil filter. There, you are good to go. Remember, keep checking the condition and level of engine oil irrespective of running as there are many factors that affect the oil. Don't take it for granted that an oil is changed after 3k, 5k, 7k, 10k. Had it been the case, the kilometers would have been stamped pretty clearly on engine oil packings. Hope you get the point.
A word of advise.....Do not outrightly trust an Afghanay and most of the Pukhtana mechanics do not live up to their legendary ustaads anymore now. Hope it helps.