Mixing oil types (Synthetic and regular dinosaurs)

[PP]

I have an opportunity to obtain a gallon of synthetic oil for free  (sealed container) and was wondering if it was safe to add this to an engine that contains regular straight 30Wt. Yeah, I use 30 and not the favored 40 because I'm always in a cold climate. Maybe one of these days that'll change. At any rate, this is 30W too.
Thanks in advance for knowledgeable answers.
Will

[Geoff]

Sure can.  They even sell  blended oil.

[luvrbus]

Royal Purple was the only synthetic ever approved for the DD 2 strokes,Davenport used the RP 40w in his 8v92 for 10 years 

[Geoff]

I don't think one gallon syn mixed in with 7+ gallons of straight 30 is going to hurt anything.

[luvrbus]

I don't think one gallon syn mixed in with 7+ gallons of straight 30 is going to hurt anything.

me either people pour Lucas into one all the time,I was just saying RP was the only approved synthetic the military used it for years   

[PP]

Thanks for the responses. I trust both of you for knowing these things. My 892 doesn't use much oil, but I was thinking of adding it to the reservoir mounted up in the engine compartment and just topping up the engine when needed so it won't even be a 1:7 blend. It doesn't leak any oil right now and I don't want to do something that will cause the seals to start leaking. They're old like me. 
Will