generator oil

I would think twice about putting syn oil in an older engine. When I switched to syn on my 1996 MH it had about 40k I had no problem. My tow car had about 80k and the pan gasket leaked within several weeks of the oil change. I had to re torque the screws twice to stop the leak. I had the same problem with my 19 year old Kohlar generator although it took longer for the leak to show up. I will go back to regular oil on the generator to see if the leak stops.

I think you will be creating your own 'synthetic blend.'
I've done the same thing with the Onan generator in our 96 Southwind. No problems.

Regular and synthetic can be mixed. You just dilute some of the better properties of synthetic. My next oil change for my generator (Hopefully this weekend if weather cooperates) will be all synthetic.

No..any oil is better than no oil. However I would change it as soon as you get the opportunity.