[smata67]

Do these sizes of tile require different adhesive? The 8x10 thinset mortar perhaps? Will regular mastic hold it? Any other advantages/disadvantages of one size over another or is it just a look thing?

 

[Ron6519]

Thinset should be used in wet areas like tubs and showers. The trowel size will be larger for the 8x10 tile. The bag of thinset will guide you to the correct size. If the tile has a lugged back, the trowel notch will be larger then if it's flat.
Ron

 

[smata67]

I forgot to mention these were wall tiles. Why have I been using the mastic type adhesive all these years? Is it because I had 4x4 tiles?

 

[Ron6519]

I forgot to mention these were wall tiles. Why have I been using the mastic type adhesive all these years? Is it because I had 4x4 tiles?

Mastic can be used on drywall outside of the tub or shower and it will last a long time. Thinset is a better product when used wth cement board.
Many homeowners used greenboard in the wet areas as they thought it was appropriate and used mastic because it was easier.
Ron