Oil? What Would You Do?

I've used Amsoil synthetic oils in my various bikes for years. I've recently parted with my other bikes and now have a small inventory of Amsoil 10W30 just sitting on the shelf. My T120 uses Amsoil 10W40 of which I also have small stock. I've tried to find some local folks that could use the 10W30 but no luck so far - just a bunch of Harleys that would be quite happy with the old Duckhams 20W50

So, my question is should I simply use it anyway as substitute for the 10W40?
Is there truly a significant difference between these grades?
Also, considering that 20 deg. C is a tropically hot day up here, maybe a "thinner" oil would be ok?

Just wondering... What would you do?
Thanks

 

Old Dumb Arse has extracted the essence of my question quite well... What happens if you mix them?

I'm not new to this by any means but I thought I'd throw this question out there and see what lurks in the bottom of the oil drain pan (which happens to be my wife's washing up bowl (…well it was once upon a time!)

If I can't find somebody that can use it, I could:
1. Most likely add the odd bottle with the 10W40
2. Use it in the lawnmower, snowblower, weedwacker or chainsaw
3. Top up my squirty oil can for many years to come
4. Sneak it into my neighbours boat engine...
5. Use it in the chip pan
6. Leave it on the shelf forever...
7. Write 10W40 on the label and get on with life.... probably the best one?

Cheers

 

Psst! Don't tell anyone but it got to 21C today (in full sun) but the "air" was still cold! Hey! in all reality, it will be option 7! (Get on with life!) inna gadda da vida! (by SIna - youtube)
Fantastic to get out these last couple of days and start a new season - I Wish Everyone many safe and happy memorable miles!

 

I don't have any concerns with the manufacturer. Amsoil is really good stuff over here in USA & Canada (NW British Columbia - 2 hour flight north of Vancouver or about 1500 kms from the Triumph Dealer!)
The open question I had: Is there a "real world" difference between 10W40 & 10W30 and what happens if I mix a little 10W30 in the 10W40?
There was another guy in town with an Africa Twin (10W30) but haven't seen him and I think he's also moved on (BMW/KTM)

 

Thanks, I'm not worried... just wondering
It's really a case of what to do with "good oil" that I don't want to use