steve is right . if you used a salution to  stimulate the rust , then you must  nutralize it .
 HOWEVER  natural rust , done in a sweet box does not need  to be nutralized becouse no acids are in volved .  simply H2O   mixing with irons in the steel .
 another thing to remeber is engine olis have rust inhbitors  this is why you use alot of oil , then  let it set .
 but again , if you used a salution like Lorul mountian or plum brown , then you need to nutralize . if you did not , no worries  just wash it down with alittle baking soad and water . then re oil and  wipe  
