Any oil ( engine oil ) mixed with the right ammount of mineral spirits ( I recommend odorless ) will work fine.
I used to mix 10w30 or 5w30 with mineral spirits and it was a great chain "grease",
I also were using pneumatic tools oil ( Stanley-Bostitch ) with great results,
Latelly, Im using Boeshield T9 and I love it.
On other hand, it's hard to tell which oil works the best or how a big difference is between them if any... I don't thing it was ever tested...
Poor chain fluid is better than no fluid at all for sure.