Oil

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

API 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

SAE Society of Automotive Enineers Measure of viscosity (how thick/runny is it?) Lower the number, the more runny (less viscous) 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 centigrade 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