i use Caltex hevoline formula engine oil, and always go to AMINA CNG at SAIDPUR ROAD PINDI for a tuning. (they are really professionals). Plugs tu 20000 k baad change karta hoon..aur air filter ko saaf rakhta hoon zaroorat paray tu foran change...and i always keep 30 psi in tires.
i suggest u to get ur kit and cylinder service. they will just open both and wash it with petrol.
this will do the trick...
best of luck......