QUOTE(izso @ Oct 24 2014, 08:58 AM)
0W20 is for the climate there. Local Tancheong recommends 5W30
from the temperature/viscosity guide/charts (within the Japanese manual), it says 0w20 can be used for climates having ambient temperatures up to 40celsius (and of course -40c)
http://www.worldweatheronline.com/Kuala-Lu...-Lumpur/MY.aspxstill well within 40c

unless you have exception usage/circumstances (eg: racing/track car), climate should no longer be the determining factor of viscosities and in almost all situation especially when dealing with modern day engine oil, one should be aiming for the lowest possible viscosity with high viscosity index (between 160-180 give/take) and aim for EOs that are API SN certified (which you may query publicly so you won't be fooled by false claims which are notorious from local EO) as recommended by manufacturers.
of course, that is not to say Tan Chong is wrong either, they may probably be still using dated EO (old API or even no API certification), or even mineral/semi synthetic instead of fully synthetics, or just merely want to standardize service schedules (eg: semi synthetic also 10k km, good luck on semis maintaining stable viscosity past 5-6k km

) so they'd rather play it safe and go with the old fashion recommendations (proton SC still uses xw40 or even xw50 with their silly synthium 1000! the irony is that most proton manuals already start to specify xw30!) such as xw30, or the old 5k km/3 months when most modern day manufacturer, shortest interval is also 10k km/6months!
i find it even surprising when even the old 4G15 engine from mitsubishi had it's service manual specifying xw30 instead of the xw50 on the sticker within the car's engine bay.
this one however can't be helped as engine oil in the early 1990's aren't as good as it is today, nor good engine oils are easily accessible than it is today.
=edit on typo/added clarification=
This post has been edited by Quazacolt: Oct 24 2014, 02:23 PM