Following the purchase of a motorbike in the barrio of Malvin in Montevideo the author has had occasional requirements to visit mechanics / sales people and discuss various items regarding motorcycles, cars and the mechanical components of both.
This artcile provides a list of useful vocabulary that he has recorded during this process; translations are not guaranteed to be 100% accurate but they have been learned to interaction with locals.

• Spanish: English
• La chapa : The number (licence) plate...
  the actual metal plate on the vehicle.
  
• La matricula: The registration of the vehicle that allows the issue of a plate.
  
• Patente Rodo: The road fund licence (annual fee to allow you to drive on the road)
• Los cambios: The gears
• Primer: First
• Segunda: Second
• Tercera: Third
• Cuarta: Fourth
• Quinta: Fifth
• Punto muerto / Neutralo: Neutral gear
• El embrague: The clutch
• El accelerador: The accelerator / throttle
• El incendido electronic: Electric start
• La junta: The seal (for example the rocker cover seal)
• El alternador: The alternator
• La cadena: The chain
• El aceite: The oil
• El aceite del motor: Engine oil
• El aceite de la cadena: Chain oil
• Lubricacion: Lubrication
• Lubricante: Lubricant
• El freno: The brake
• Freno de disco: Brake disc
• Pastilles de freno: Brake shoes/pads
• Las ruedas: The wheels
• La horquilla: The fork (suspension fork)
• La amortiguacion: The suspension / shock absorber
• El manillar: The handlebars
• La nafta: Petrol (gas)
• El tanque: The tank
• El pie: The stand (literally the foot)
• El cuadro: The frame
• El asiento: The seat / saddle
• Las aforjas: The panniers (saddlebags)
• Los guardabarros: The mud guards
• Caño de escape: Exhaust/Tail pipe (literally pipe of escape)
• Los espejos: The mirrors
• La garantia: Warranty/Guarantee
• Arreglar: To fix
• Andar: To ride (in Uruguay/Argentina)
• Manajar: To drive (also used with motorbikes by some people)
• Montar: To ride (in other countries, literally to mount)

This list is not designed to be exhaustive but may prove useful if anyone is dealing with mechanics in particular, most of the ones I have met do not speak English but with some perseverance it is perfectly possible to make your message understood - never under estimate the power of sound effects and charades in the absence of the correct words.