I have an 06 GSA, so not quite a 10 variety but not greatly different.
Over the 54,000 miles of its happy existence it has had poured into it's bowels:
10-40
20-40
20-50
and probably some other something-something's as well, I really do not remember nor do I write it down.
More importantly:
(a) The oils came from not one manufacturer. I have used: Castrol, Elf, Texaco, Esso and Fuchs to name but five and various others no doubt.
(b) They have at assorted times been mineral, semi-synthetic and fully synthetic.
(c) They have been mixed and / or topped up (without draining what was residing in the sump already) as needed between the main oil changes each 6,000 miles.
So, in 56,000 miles:
(1) I have had nine full oil changes and between times assorted top-ups, some quite major.
(2) At assorted times 'old' oil (whatever less than 6,000 but more than zero miles of use is called) has been mixed with 'new' oils.
(3) The bike has run at assorted air temperatures between -5c and +35c, often all day with limited stops and been revved fully, right around the scale.
(4) At any one time it is probably running on a hybrid of semi and fully synth, made by perhaps three different manufacturers, with maybe a splash of mineral if that is what went in.
(5) It is averaging perhaps a rating of 15-45 for the sake of argument.
Of course, nobody makes a 15-45 multi-grade oil and no company called Castro-El-Tex exists, nor makes a mineral synth.... but (and here is the really important bit)........ I decided to never tell my bike, so it would never know. And, you know what (as what you do not know can never hurt you) it has never complained once.
Mix away Mr Snerkler, it really will not go bang.
Better still, it will remove forever the risk of that one moment of deep dread when you find yourself 50 miles from civilisation, staring at a sight screen that is 9/10's empty and there being just a two litre dusty 10-40 4-T bottle on the shelf of Mrs Miggin's petrol station, made by Rick (or did it once say Rock?).
PS The only oil derived substance it really objected to was diesel.