Thnaks Imran bhai!
I never thought of it that way. Previously it has happened twice that the mechanic used ordinary oil and that was really thick oil and the bike was very bumpy.
As regards my search Mobil 1 synthetic ATF is 7.5wt and ppl use dexron and Mobil 1 as ATF due to their light weight. Fork oil is really expensive as compared to ATF in foreign countries.
I already poured warco ATF in my bike forks, but didn't felt a lot of difference in damping. I think either springs are hard and not compressing on jerks, or still the used fork oil is thick.
I will look for some thinner oil from some car shock repairer and will also change ball bearings (golian) in under handle bar joint, that also make thak thak noise on jerks.
Would you please tell what else can go wrong in addition to springs and oil for shock softness and how to check.
I mean bushes or some thing else.