I cant speak for the OS .81 as I have nver owned one. I have owned many OS products over the years and have always enjoyed using heir engines. Although I have used the Saito .82 ALOT. It has been a great motor and very easy to live with. I will agree that the oil residue does get old. it was very hard on the covering of my Reactor. To be honest I think you would be good to go either wy.