First... turn off your Nitrous bottles....
This might get a little extreme, but you should not keep dirty oil in your motor. Do an oil change before storage, run the motor for a couple of minutes and that's it. DON'T start the car up mid winter. Cold starts are the ABSOLUTE worst thing for any motor, and if you don't need to... don't do it. Disconnect the battery and cover the car with something that breathes (not plastic). Fill the gas tank and if you can put the car on jack stands to relieve the tires from the weight. Plug up the muffler with some rags too (rodent prevention - no joke). Good Luck.
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-- RANDY SPARRE --