3 months storage
 

Is there anything else recommended for storing my 91 300CE
for 3 months besides a fresh oil change, tank full of gas? Is it recommended to remove the neg. cable on the battery? I will also park it on wood to keep the tires off the concrete garage floor.

How fresh is the antifreeze? Old antifreeze loses it's corrosion-inhibiting additives.

storage
 

I would disconnect the positive terminal

You could add some fuel stabilizer -- but for only a few months?

According to a Sta-bil website, " On average, the life of your typical gasoline is extended from 2 months oxidation life without STA-BIL up to 15 months will STA-BIL. STA-BIL keeps your gas fresh for quick starts... What Kind of Equipment Needs STA-BIL?
Any equipment that's not used often, or stored for 60 days or more, needs STA-BIL."

Can't hurt.

I'd put a tarp under the car for a moisture barrier since concrete "sweats", but then again, we're talking about 3 months. :)

Any mice issues? That can be a REAL problem.

Inflate the tires to 60psi to reduce the chance of flat spots. Leave yourself a note on the dash so you don't forget to correct the pressure before you drive it again!