Bhai we were also using 20w-50 since late 80's in several cars but when 12 year ago when I joined Pakwheels in 2006, i was also satisfied with 20w50 but here experts & seniors educated me the relevant specs. as per car engine & several other conditions. 20w50 is quite think and mechanic usually recommend to cover up their fault as it is so heavy and they used it for hiding engine noise which emerged due to their own fault. Also if they know some lackings in their packing/seals, they also hide it by 20w50 
Similarly when people want to dodge while selling car, they also use this "Garha Oil" trick, by garha they mean 20w50, this trick temporairly lowers the sound(when car is in parking position)
I came to opinion that wethet old or new, use only recommended fuel specially providing by Manufacturers
Usage of 20w50 leads:
Crackling sound,
Sludge.
Damaged timing chain tensioners.
Seized timing adjusters / variators.
Poor gas mileage.
Excessive engine wear.
Premature oil pump failure.
Premature tappet adjustment failure.
Clogged PCV systems
If u r satisfied with 20w50 what can i say. You know your engine.I also corrected my Oil grade which ran 113,000 Km on odo meter after 10 years by considering Dair ayed durust ayed
Simply think if 20w50 is anywhere relevant, why Pak Suzuki is not blending or packing this grade? They are providing only 10w40 Multigrade engine oil in 2 variants
API SG(Non Synthetic)
API SM(Synthetic)
@umarkhan1
Can you provide diagram how to bypass STAP00B? Can 12 degree option better achieved by Timing Gun?