QUOTE(delsoo @ Aug 22 2016, 12:12 PM)
http://www.castrol.com/en_gb/united-kingdo...sity.html\The front number represent the viscosity of the oil when it's cold , the number behind means the viscosity of oil when it's hot ?
a)From the link I provided above:
QUOTE
AE Viscosity Grade Low-Temp (°C) Cranking Viscosity, cP Max Low-Temp (°C) Pumping Viscosity, cP Max with no yield stress Kinematic Viscosity (cSt) at 100°C Max Kinematic Viscosity (cSt) at 40°C Max High Shear Viscosity (cP) at 150°C Min
0W 3250 @ -30 60,000 @ -40 3.8 - -
5W 3500 @ -25 60,000 @ -35 3.8 - -
10W 3500 @ -20 60,000 @ -30 4.1 - -
15W 3500 @ -15 60,000 @ -25 5.6 - -
20W 4500 @ -10 60,000 @ -20 5.6 - -
25W 6000 @ -5 60,000 @ -15 9.3 - -
20 - - 5.6 <9.3 2.6
30 - - 9.3 <12.5 2.9
40 - - 12.5 <16.3 2.9*
40 - - 12.5 <16.3 3.7**
50 - - 16.3 <21.9 3.7
60 - - 21.9 <26.1 3.7
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.
QUOTE(delsoo @ Aug 22 2016, 01:49 PM)
I don't hv the owner manual..... I am not the direct owner of the car....
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