@asadsethi
I always use 15W-40 viscosity oil (Diesel specific) in my Diesel cars & used to change oil @ 5000Km & never got performance & oil reduction etc type issue.
Mostly the modern oil are complaince to both (Spark ignition & Compress ignition) IC engines so it shudnt harm But u must find some Modern Engine Oil specifically for Diesel complaince.
May not in the line of most Hi tech But i have found Delo Gold very good lube to be used in Diesel Engines & easily available all over Pakistan.