MKK123
Here is brief reply of your questions,
Any notation where W is mentioned between two numbers mean it is a multi-grade oil (10W-30 or 20W-50).
It meets the maximum low-temperature cranking and pumping viscosity and min & max viscosity @ 100 oC. These limits are set by SAE (Society of Automotive Engineers, USA), for engine builders for oils to be used in these engines.
Low-Temperature Cranking Viscosity, cP, Max
10W, 7000 at –25 oC
20W, 9500 at –15 oC
Kinematic Viscosity,(cSt
at 100 oC)
SAE 30, 9.3 - 12.5
SAE 50, 16.3 - 21.9
10W-30 oil meets both limits mentioned above & 20W-50 also meets both viscosity limits.
10W-30 is less viscous (thin), as viscosity is between 9.3 to 12.5 centi Stoke @ 100 oC. It is used in new model cars where it is recommended. It is more fuel efficient.
20W-50 is more thick or viscous oil (viscosity 16.3 - 21.9 cSt) and mostly used in bit old cars or if any car is consuming oil due to worn rings and clearances etc.
2- Another important aspect is to read API level mentioned on oil cans.
For petrol cars it start with S (spark ignition), like API SJ, SL, SM, SN (SN is top most oil in Pakistan, in 5W-30,10W-30, or 10W-40 viscosity)
For diesel engine oils it starts with C (Compression ignition engine), like API CF-4, CG-4, CH-4, CI-4 etc (API CI-4 is top spec in 15W-40 viscosity)
1- 2003 Prado = You can use API SL or SM in 20W-50 viscosity
2- 2014 Vigo= Owner manual to be consulted. You can use API CI-4 in 15W-40 viscosity, which is top spec oil
3- 2013 Altis= API SN in 10W-30 or 10W-40 viscosity
4- 2008 Cultus= API SJ or SL in 20W-50 viscosity
5- 1994 Landcruiser= API SF, SG or SL in 20W-50 viscosity
Q#2
Changing oil and filter at 5000 km for API SL is ok. For SM, SN or CI-4 you can even go higher mileage. The filter quality should be good.
For API SF of SG, 3000 to 3500 Km is ok.
Hope this know-how will help you and other like you to manage your vehicle properly. Oil of major oil companies like Caltex, Shell, TOTAL, Fuchs, PSO should be used both mineral or synthetic.
Regards
