my 2004 pros giving the following figures
without ac, city driving around 10.3km/L petrol & around 135km on CNG 55 tank. On highways, around 16km/L @120km/h and around 14km/L at around 140km/h. whereas on cng, m getting around 200km/rs.800 fill.
with ac, city around 9km/L on petrol & highway around 15km/L @120km/h. On cng around 125km/rs.660 fill and around 180km/rs.800 fill. M using stock plugs, SN DRAGON 10w40, stock setup
You switched to 10w40 which is good cux 20w50 is thick for starters. But keep in mind that seals and gaskets adapt too the thicker oil with time and might leak if u go thin on the oil. So keep checking for leaks. Get ur CNG tuninig and regularly clean ur intake, every week. doesnt take more than 5min. Ur petrol figures arent that bad, i assume u take the d16 for a fun ride alot
if u want good figures, keep a soft foot. rest you r pretty good