You will likely get as many people saying you can as saying you can't. For example, Amsoil told me not to mix their XL line of oils and Redline told me I could mix their car oils. I done it in the past with conventional oil and synthetic oil to make my own "synthetic blend" with no adverse results. I'm about to change oil in both my bikes and will be trying a mix of two different Redline weights. I think it is probably OK to mix the two you have but most people will probably say it is not ideal .