Am look for (ideally) Castrol GL-4 80W-90 oil, but any good make equivalent will do.

My problem is I only need a max of 1 litre but the smallest they seem to sell is 5 litres !

Anyone seen it in the 1 litre plastic bottles ?

Just thinking that most cars are now FWD so oil is shared. Have you tried a Kubota Tractor dealership? They may have something.

Or scooter shops have rear case transmission oil in 250ml bottles I think I've even seen Castrol so it maybe the same stuff.

Many thanks for that - had not thought about scooters (or tractors !)

Diff oil for pick-ups would be about that rating.

SAE 90 or 80W90 gear oil is often used for Older tractors, implements like rotary hoes, slashers and truck transmissions.

A farm machinery or truck workshop might share some with you for the right tip.

Some newer tractors with power-shift trans, more hydraulics and wet disc brakes use fancier stuff.