It is lubricated and cooled by the engine lubrication and cooling systems. This increase in moisture provides vaginal lubrication, which reduces friction. The moving parts had friction, which required lubrication and replacement due to wear. Cutting fluids degrade over time due to contaminants entering the lubrication system. The coefficient of friction is lower than with boundary-layer lubrication. It includes the study and application of the principles of friction, lubrication, and wear. The science of friction and lubrication is called tribology. Both vaginal lubrication and vaginal dilation decrease. European specification cars used dry sump lubrication. Powerglide cars got a version which had hydraulic lifters and full pressure lubrication. The channels behind the grease nipple lead to where the lubrication is needed. This pericardial sac is filled with a serous fluid for lubrication. The engine makes use of a wet sump designed lubrication system. Arousal disorder means lack of vaginal lubrication. They need no lubrication and minimal maintenance.