MF there is a reason there is still plenty of 4 stroke - that deal is poor.

1l of full synth 2 stroke for $13 is a great deal - 1l of 10w30 4 stroke oil for $13 is seriously bad.

1l @ $13 = 5l @$65. That's squarely in Castrol edge territory. I would take it back and go down to SCA and pick up this if you want to try full synth in the briggs https://www.supercheapauto.com.au/p/castrol-castrol-edge-engine-oil-10w-30-5-litre/516277.html

I would not consider putting expensive oil like that in a briggs. 1 its still pricey at 40% off, 2 it is API SN which means low zinc (flat tappet engines need zddp to prevent wear).

You need a few things in a mower oil - protection at start up (ZDDP), protection whilst hot running (boron), a good total base number (as oil dilluted by acids from combustion will become more acidic and pit and eat away eventually), and a good shear stability (resistance to thinning after high heat cycles).

Thus in a perfect world, you would use an oil with an API before SL, and a semi or full synthetic (better shear stability). Aldi's one may offer this - but I doubt it. It is probably the cheapest 10w30 they could find.

The other way around shearing is using a mineral straight weight oil - hence SAE30.

However, 15w40 is very shear stable. Given time, it will shear slightly worse than a 30w, BUT I know you will change the oil regularly and it will not be left for years on end.

If I were in your situation, I would pick up one of these when you go back to repco to pick up the coolant https://www.repco.com.au/en/oils-fl...5w-40-engine-oil-5l-pm15w40-5/p/A9491748

Nulon mineral 15w40 - shear resistant, shedload of ZDDP, good TBN, AND $13 for 5l. I personally have about 5 bottles from when it was $10/5l, but still a deal.

Plus its aussie - and to quote Scomo - "how goods that?" Great!


PS - picked up the air filter oil spray today. Only thing to note if you get some is it turns oiling the air filter into a 5 minute operation - it comes out cold and practically freezes the foam, so you have to wait for it to thaw out a few minutes (30 sec in the sun) before you knead the oil through.