Look there are confusions flying around this thread....would request all of you to go through this web page at least....
INDUS MOTOR COMPANY LTD - Imported Vehicle -
Secondly, the petron 4L is around 1650 and TGMO (Tin packing) is around 1850 from the dealership (toyota islamabad)...now they have Petron available in large drums so i think you dont need to buy them in packing of 4L or 3L....(the total charges upon actual quantity poured)
Thirdly, the owner's manual of Corolla, which covers Altis as well, never recommends 10,000km oil change interval. it is 5000 for gasoline and 2500 for diesel cars.
Fourth, what i have learnt from them is Petron (20W50) is mineral where as TGMO is semi-syntetic.....both are good oils from the reviews i have gathered from Pakwheels and other sources. Petron can sustain an ODI of 5000 kms as well but of course it's the owner's choice in the end....your car comes factory filled with this Petron (20w50)..
Fifth, if your car is still under warranty and you want this to remain intact use this oil and maintain a proper record of oil servicing through dealership ......it is not a bad oil after all....have heard bad comments about Honda oil but Toyota has a decent product line.....
I myself would like to pour 5W30 (Tin pack) upon first oil change of my GLi.