20-50 thick oil hai mostly used for old engines as they are week in compression, make noise, and cause leaks so thick oil prevent these problems moreover iska changing interval bhi 2500 km hota hai kuch log 3000 km tak bhi chala lete hen. moreover you can also do one thing k pehle 20-50 daal kar running puri ker len for 1000km and then change back to 10-40. use shell brand as it is good for our local weather conditions.
