Oil by aAVJC3


              Purpose of oil
• Lubricate
• Cool
               What is oil?
• Petroleum product
• Up to 25% artificial additives
  – Detergents
  – Anti- foaming agents
  – Sulphur containing compounds
  – Viscosity
• Degrades
• Diesel oil has a hard life
              Oil grading
• API - quality
• SAE – viscosity
• American Petroleum Institute
• 2 letter designation eg. CD
• First letter
  – S for petrol/spark ignition engines
  – C (or D) for compression ignition diesel engines
• Second letter denotes quality
• Higher the second letter, the better the quality
• Always use quality specified in your manual or
  higher eg if CD specified can use CG
• Society of Automotive Enineers
• Measure of viscosity (how thick/runny is
• Lower the number, the more runny (less
• Followed by W for winter eg 10W
• Modern technology allows multigrade oils
         Multi-viscosity oils
• Eg 20W-50
• First no. still relates to cold viscosity
• Second no. relates to viscosity at 100
• The higher the second no. the les the oil
  thins as it warms up
• Due to polymers which uncoil and tangle
  up as oil heats up, making it more viscous
    Why is viscosity important?
• Low oil viscosity
   – means easier starting and running –don’t have to stir
     the oil so much
   – Oil is easily pumped to all parts of engine – less wear,
     especially on starting

• High oil viscosity
   – Oil clings to surfaces better
   – Seals piston rings better – compression
   – Harder to pump to all areas of engine

• Compromise required
                      Clean oil
• Change oil regularly
• Renew filters
• Use correct oil

• Avoid load-free/cold running
• Monitor oil pressure
  – Gauge
  – Warning light
                   Changing oil
• Wear gloves – used engine oil is highly
  carcinogenic 
• Run engine – warm oil is easier to get out
• Ideally pump out oil
• Replace oil filter
   – Remove old filter
   – Remove any old o-rings
   – Fit new o-rings correctly
      • Seating
      • Wipe with clean oil
• Dispose of old oil correctly

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