They only had 6 qts and my sump hold 6.9 qts. I'm due for a change now so should I...... 1 - Top off with some US Castrol 0W30? 2 - Top off with some Amsoil 0W30? 3 - Top off with some M1 0W30? 4 - Just fill it with the usual Amsoil 0W30 for now and wait until next OCI (~2 months) to find another qt of GC? Darn, I really wanted to try this stuff.