The reason I ask is that you want to insure that your mortar is that I would think you need to insure that your mortar is rated higher than the max heat of your oven to prevent failure.
When I looked the product up on 3M's site, this is what it says:
"When properly installed, sealant helps prevent the spread of fire, smoke and noxious gas. In addition, this product acts as an acoustic barrier by minimizing noise transfer (STC-Rating of 54 when tested in a STC 54-rated wall assembly), helps create a smoke seal for systems requiring the optional L-Rating, meets the intent of LEED® VOC environmental regulations, meets International Building Code (IBC) and other key life safety building code requirements."
I may be wrong, but I believe this is designed to be used on fire barriers as opposed to ovens or furnaces. i would look for a mortar that is going to be rated at 2000+ for your oven.
Here is a link to the Rutland which is offered in some TSC stores.