Grease is oil that has a thickener added to it. Synthetic grease uses synthetic oil. While synthetic grease might be twice as expensive as conventional petroleum grease, the advantage of using synthetic grease is that it can keep cars and trucks on the road longer between servicing.
Synthetic grease is more likely to withstand the effects of heavy rain and other high water events. Synthetic grease does not wash out or emulsify the way petroleum grease can.
Most synthetic greases can withstand temperatures of at least 300 degrees Fahrenheit before "melting" and running out, compared to about 240 F for petroleum grease. This makes synthetic grease especially valuable for lubricating brakes, non-drive wheel bearings, differentials and transmissions.
Conventional petroleum grease can withstand approximately 700 pounds per square inch (psi) of pressure before the grease film is ruptured, and there is metal on metal contact. Synthetic oil can withstand 3,000 psi before failing.
The rust- and corrosion-resistant properties of synthetic oil provide better protection and longer life to bearings and chassis lube points.
