Whereas most accountable Mercedes homeowners bear in mind to vary their engine oil moderately steadily, not everybody remembers to take care of the opposite lubricants on the automotive. This text focuses on arguably probably the most severely uncared for fluid: the gear oil within the rear differential.


Most Mercedes 126 automobiles have “open” differentials, although a couple of of the later fashions got here with limited-slip differentials. The previous don’t require a lot consideration and are, the truth is, extraordinarily sturdy. Scorching-rodders have discovered that the rear differential on the 380SE can deal with as a lot as 800hp by the rear wheels. However, that does not imply we will overlook about it utterly. The gear oil needs to be modified at roughly 100,000-mile intervals, or each 50,000 in extreme service. If left in too lengthy, it’ll ultimately lose its capability to lubricate and begins to resemble frothy pea soup! (It does not scent too good, both!)

Fluid capability is barely about 1.5 quarts, so there isn’t any excuse to not use the “great things.” Amsoil, Redline, and Royal Purple all make high-quality artificial gear oils, usually with 75W-90 viscosity. Simply as with an oil change, that is greatest executed with the fluid at working temperature. The 2 plugs within the differential — higher fill and decrease drain — take a 14mm hex key and are normally extraordinarily laborious to budge. An extended breaker bar will likely be required. Just be sure you loosen the filler plug first, as a result of when you take away the drain plug after which discover the filler is caught, you’ve got obtained a little bit of an issue. Melting an ice dice within the filler plug’s 14mm-fitting might assist loosen it by thermal contraction.

Refilling is far simpler with a small oil pump. Merely fill till the gear oil is stage with the filler gap; when it begins to seep out of the threads you are executed. To make sure an correct fill, the automotive needs to be stage throughout this operation, although this isn’t crucial. In the event you go away the rear of the automotive up on jack stands, a slight overfill will ensue. Torque the plugs to 50Nm (37 lbs/ft).

Source by Richard M Foster