I have a os46fx to store for a long time
I plan to fulfill it with SAE15 oil (the one I use for my car engine) and place it in a plastic bag that I will vaacum seal

is that a good idea?

SalmonBug,

Run your engine at maximum speed and stop it by disconnecting the fuel line, so as little as possible fuel residue, or methanol (it is hygroscopic) remain in the engine.
Afterwards, soak it in ATF, or prefferably Marvel air tool oil and store it in a sealable plastic bag.

Sincerely,

I'll second the air tool oil or atf, and be liberal with it too, you want to be sure it gets to the bearings. Motor oil is better than nothing, but it doesn't have the corrosion protection of atf or air tool oil.

JJ

Marvel mystery oil "dry up" and leave a nasty residue. On the other hand I've disassembled automotive transmissions that were stored in the rain and slop and as long as there was ATF present there was no rust. Modern ATF is the bomb for protecting. That's all I use.

could you please tell me what you call "ATF"?

automatic transmission fluid...

ah ok, in my language we call that "huile pour boite automatique"

marvel oil is ok for short term, (winter) storage. long term is definatly better with automatic transmission fluid. ( A.T.F) liburaly into the carb, vent & cylinder,(with glow plug removed). wrapped in a diaper & in a plastic bag. when you go to use it next time, drain oil from it & use an old glow plug to run it, as the elements in our plugs dont like all that oil getting blasted on them, just like sparkplugs in your car, oil will deposit on the hottest item in the combustion chamber. mildbill

I've stored engines completely submerged in ATF. I used a coffee can, put the motor in it then poured the atf in. Top on and then tape it. Later you just pullthe motor out, drain and go....