My hobbie shop is still usless and i bough 60 wt for the rear and im wondering if mixing 1/2 of a bottle left of 40 wt with 1 of the 60 wts i bough will give me close to a 55 wt oil.

My math. 1/2 bottle =1 part. 1 part 40 wt with 1 part 60 wt = 50 wt.
1 part 50wt with 1 part 60 wt = close to 55 wt.? does that work??