Manchester had eased into a 4-0 lead and were seemingly cruising at 5-1 when the Midlanders launched a recovery. Oscroft, Sophie Linney and Elizabeth Palmer all scored before Oscroft grabbed the late equaliser.
Mhairi Nurthem scored four in Otter's 14-6 defeat of Caledonia.
In the men's Super 5s, Lancaster relaxed a little too early against Bristol after leading 17-14 in the last period. Bristol then scored twice through Ashley Castle and Carl Wyatt - just too late to deprive Lancaster of a vital 17-16 win.