Sir Jackaroo,

1. I recall sir that most service stations (Petron, Caltex, Shell) offer a monograde SAE 90, API GL-4 gear oil which you may consider for your transmission as replacement for the multigrade spec that you require. It is available in 1 liter, 1 gallon, pail and drum packs.

2. For the API GL-5 SAE 80w90 gear oil. Castrol markets this in 1 liter containers/drums locally. I have seen it in some autosupply and service shops in Banawe like Megamotion.

To know if it has an LSD or open differential raise both rear wheels above the ground (preferrably in a service station). With the rear parking brake off spin one of the wheel. If one wheel spins opposite the other then it's an open differential. If it spins in the same direction then it's an LSD.