:welcome:
In general,
White smoke under load = worn rings
White smoke backing off = valve guides
Is it using oil? Bad valve guides will also cause oil consumption.
Nothing you can pour into the engine will ever fix anything, just mask the symptoms till the engine goes bang.
As it is a "toy" you will have to make call on it.
If the engine has a C I linner then no great drama but if it is plated running on bad rings will kill the engine.
Again depends how long you want to keep it for.