Cultus does not good with low weight oils (starting with 0 & 5).
One of a known guy used Zic OW in cultus, but was not satisfied with the results.
Feeding 10W oil should be the best.
Availabilities are
10/30
10/40
15/40 (zic-m)
My preference will go for Toyota's Tin Pack (Made in Japan) 10/30 API-SL grade oil. Its availability is rare, but this can be good oil to run upto 4K for sure. And if Engine is in good condition or new, then even can change it after 5K.
Price is Rs. 3200/4L
Or
Go for PTT Performa's 10/40 Semi Synthetic oil. Perhaps you will like it most. Change interval is 4~5K depending upon engine condition.
Price is ~ Rs. 2400/4L
Or
Go for Kixx's 10/40 Semi Synthetic oil with change interval as 4~5K.
Price is ~ Rs. 2400/4L