24 May Where Oil Goes and What it Does
A typical engine contains hundreds of parts, none of which could function properly without oil, a dynamic enabler of performance which must lubricate, cool, protect, seal, actuate components and more and must do it all while exposed to tremendous heat and stress. The following engine components are the key areas where oil goes inside your engine and what it does once it’s there.
Variable Valve Timing (VVT)
To increase fuel economy and reduce emissions, most modern engines use VVT systems to adjust when the valves open and close. VVT systems use motor oil as a hydraulic fluid to actuate cam-phaser components. Solenoids, like the one shown here, control cam-phaser timing. These solenoids contain tiny openings through which the oil must flow. Even minimal varnish or deposits can disrupt the system, triggering a check-engine light. The oil must maintain viscosity to function as a hydraulic fluid while resisting deposits to maximize VVT system performance.
Valve seals prevent oil from running down the valve stems. This keeps the oil on valvetrain components and prevents it from entering the intake and exhaust ports and burning, increasing oil consumption. The oil must condition these seals to prevent drying, cracking and leaking. The oil also helps cool the valves and control cylinder-head deposits, helping prevent valve sticking.
Wrist Pins & Undercrowns
Crankshafts eccentrics splash-lubricate the cylinders, wrist pins and piston under crowns. Some engines have small nozzles that spray oil directly onto the wrist pins and undercrowns. The rapidly spinning crankshaft causes air entertainment in the oil, creating foam. If foam bubbles in the oil pass between metal parts, they collapse and cause metal-to-metal contact. The oil must contain anti-foam additives to quickly dissipate foam and must also contain detergent additives to help keep the wrist pins and undercrowns clean.
The seals at the ends of the crankshaft keep the oil inside the engine to condition seals to prevent drying, cracking and leaking.
Connecting Rods & Main Bearings
Combustion drives the pistons down the cylinder, creating intense pressure between the connecting rods, main journals and bearings. Oil molecules act like microscopic ball bearings that support this pressure and allow the rods and crankshaft to rotate without metal-to-metal contact. The oil must maintain its protective viscosity despite increased pressures, temperatures and shearing forces. If the fluid film weakens, the oil will squeeze from between the journal and bearing clearances, resulting in metal-to-metal contact and bearing wear.
The camshaft and lifters open and close the intake and exhaust valves. To prevent wear, the oil must form a strong fluid film that separates the cam lobes and lifters. It also must contain robust anti-wear additives to maximize the life of the camshaft and bearings,
AMSOIL Signature Series 0W-20 Synthetic Motor Oil does an excellent job protecting against cam wear in rigorous, third-party testing.
Pistons, Rings & Cylinders
The pistons compress the air in preparation for combustion. The piston rings perform several critical functions: they must seal the combustion chamber, return excess oil on the cylinder walls to the sump and transfer extreme piston-crown heat to the cylinder walls.
To prevent wear despite intense heat and shearing forces, oil must maintain a strong, consistent film between the rings and cylinder walls. It also must prevent deposits that cause ring sticking, increased oil consumption, compression changes and low-speed pre-ignition (LSPI).increased
Signature series synthetic motor oil achieved 100% protection against LSPI in the engine test required by GM dexos1 Gen 2 specification – zero occurrences were recorded throughout five consecutive tests.
Oil Galleries & Passages
An engine contains an intricate network of galleries and passages that carry oil to its components. Passages in the crankshaft carry pressurized oil to the rod and main bearings, while similar passages in the upper end carry oil to the valve-train. Oil that thickens in the cold can fail to flow through narrow passages and starve the engine of oil. Sludge, meanwhile, can plug passages and have the same effect. Oil must remain fluid when the temperature drops and must prevent sludge.