Repco has Penrite Motorcycle 4 Stroke Semi Synthetic 10W-30 1L on clearance for $7, cheaper than SCA and Autobarn. Even though it is a Motorcycle Oil it can be used in Lawn Mowers where a 10w30 Oil is recommended.
https://penriteoil.com.au/products/mc-4st-semi-synthetic-10w…
Can't find where to put in my ego lawn mower