yes....I forgot that option.....A3/B4 in 5w30....hths is also 3.5 min!Where im at there is 2 types of 5w30. A5B5 stuff which is resource conserving and thinner than A3B3/B4 which is thicker. Between the two its 100c cst 9.9 vs 11.5ish. hths is also different between the two.
Dunno which is safe to run in lawn mower but sae30 here is around 11 cst at 100c
But it is a rarity over here....because 90% of 5w30 grades here are DPF oriented (Low/Mid saps).....look my above post for specs.