What you could do is use all GTX except with 1 quart of Mobil 1 Racing Oil 0w=30, an oil that boosts the additive package, as discussed elsewhere on bitog.
Except for the M1 Racing costing between $16.00 and $22.00 a quart (albeit GREAT, but
very low starting TBN oil, so maybe not so 'great' for street/long OCI use) depending on where/how it is purchased, does NOT make this a viable economic choice to just use up some GTX, and it STILL might not meet Dexos 1 specs,
if that is a concern.