a)From the link I provided above:

http://bobistheoilguy.com/putting-the-simp...into-viscosity/

b)The grades denoted with the letter “W” are intended for use in applications operating in low-temperature conditions , i.e the SAE requirements are as follows :-
0W for -40*C ambients engine starting;
5W for -35*C ambients engine starting;
10W for -30*C ambients engine starting;
15W for -25*C ambients engine starting;
20W for -20*C ambients engine starting;
25W for -15*C ambients engine starting;

c)In Malaysia, typical coldest temperature we encounter is 24*C or thereabout .
Therefore according to SAE, Malaysians don't need multigrade engines oils with ALL the cold temperature ratings of 0W;5W;10W;15W;20W and 25W.

d)Can we use xW then ?
Sure , we can.
Is it necessary ? No, it's not necessary.
We don't benefit from it's intended use of starting engine at ambients of -40*C to -15*C as our lowest ambient temperature is around 24*C in the early hours of the day.
Hence, according to SAE we require only monogrades, not multigrades.

e)On monogrades SAE 20 to SAE 60....., my rule of thumb on minimum engine starting cold temperatures are :
-10*C and above for SAE 20;
0*C and above for SAE 30;
10*C and above for SAE 40;
20*C and above for SAE 50 and
30*C and above for SAE 60.

f)Since our lowest ambient is 24*C (and basing on my rule of thumb above) , monograde SAE 50 would be the thickest grade allowable for engine starting in the early hours of the day.
Can we carry out engine starting here for SAE 20; 30 and 40, besides SAE 50 ?
........ Refer to (d) above.

g)So much for engine starting for 'cold' temperature regimes that is regulated by SAE/API.

h)Now, what oil viscosity grade OP should use in his Proton Saga ?
This ....... is none of the business of SAE/API!
OEM's calls the shot here.

IIRC for 4G13 and 4G15 engines , Proton(Mitsubishi) recommends from 10W30 ...... 10W40 ...... 15W40 ...... and 20W50.
I would see if I can provide a link ...............
JMHO

Edit:OP, does your engine come with carburretor or fuel injection system?

This post has been edited by zeng: Aug 23 2016, 02:43 PM

I use petronas fully RM2xx, but I change it every 6 months.

Whoa, rich man! You drive a lot, do you?

engine sure gt these 2 components , right ? Btw , Thanks for the info above

Yes. Cheap Mineral oil is definitely thicker and 20W50 is said good to aged engine if oil loss happened. Always go for semi or fully synthetic if no problem with the engine.

No, it's either or.
An engine with carburretter fuel system , doesn't have (electronic) fuel injection system ...... and vice versa.

i think it's carburretter fuel system ..It's saga . So , i dont expect the proton adopt electronic system which is more advanced..

do you mean if the engine gt oil leak , then the engine cant take lower viscosity 10w40 anymore?

Here is a link on Shell Helix Ultra 5W40 fullsyn UOA by a fellow Malaysian on an USA oils forum.
http://www.bobistheoilguy.com/forums/ubbth...opics/3986194/1

Turbo engine.. drive mostly highway round trip.
I planned to use semi synthetic now.. jimat sikit.

Woah! didn't expected that we have others who actually do UOA

he a LYN poster as well? i'll pin it up on the first page of my thread and wish to tag/credit/shoutout to him as well

Ya but you're also using rm200+ oil while there are plenty of much cheaper FS oil.

If you observe proton subforum, there are iriz owners using petronas syn7000 fully synthetic oil at proton SC, around RM250~270 if not mistaken.

i would recommend fosser, i serviced my 5yo persona at auto marque near kelana jaya. cost me rm130 (labor+filter+oil), manage to reduce my fc from 8.4L/100km to 7.8L/100km (mainly due engine), I can feel my engine rev lesser than normal. so i consider a win for me. already used it around 4000km.

+1 , concur with therain01 in your context.

I abandoned Petronas Mach 5 SF/CC SAE 40 for Petronas Mach 5 SM/ACEA A3-B3 15W40 ..... as my Wira carburretor engine requires SG.

For the same price,I later upgraded the specs to minerals Urania Supremo CI-4/ A3B4/SL 15W40 (which basically is a Heavy Duty Engine Oil for diesel engines) till todate.

Now semi synthetics SL/A3B4 10W40 can be had during promo , at lower price than CI4/SL/A3B4 and begins to flow into the other multi-port injection Avanza.

I'd no success in securing locally a 20W50 with A3B4 specs ...... and don't have a need for it ..... as all 3 engnes are not leaking oils.

Since yours is a carburretor engine, I would recommend a mineral A3B4 15W40; or a semisyn A3B4 10W40.
If you so wish,and have budget for a fully synthetics 0/5W-40 A3B4, why not?

Just my 2 sen.

This post has been edited by zeng: Aug 23 2016, 02:31 PM

Wah so many rich people apparently!

Last time we see petronas fully synthetic rm200 already say it's super expensive.... Now rm270 still got people support... Future selling rm350 also no problem... As long got AMG Hamilton image sure bagus can support one.

Just wondering petronas lubricant so good? I thought other brand from overseas are local better than this local brand?

Just how many of you do UOA here, so far i only knew you n now plus him

He is on this forum as well, on saga thread

I think people feel good using it might be partially due to their marketing prowess, but this is strictly my opinion

I think their PCMO are very expensive but then their heavy duty oil suited for gasoline engines is quite a bargain, I would use it on my old car

there are other lube brands that can be better, but people arent aware of their existence, probably due to lesser marketing budget n lack of distribution channel