Recently acquired a 1972 Benz 280SE 4.5 and after a routine service, some concerning issues have surfaced. Following a Virginia inspection and subsequent new front tires and a full checkup with fluid changes at a national chain, the classic Benz started showing signs of distress. Initially, an idle problem was addressed with Techron and a switch to 91+ octane gasoline, which seemed to resolve the issue.
However, within the last week, two new problems have emerged, causing worry about this vintage vehicle. Firstly, the engine has become noticeably louder, producing a sound described as akin to a helicopter, not a harsh metallic clanking, but a distinct and unusual engine noise. Secondly, the oil pressure gauge is behaving erratically compared to its previous stable readings. Before these issues arose, the oil pressure would consistently sit at about one-third at idle, and quickly rise to the maximum when accelerating. Now, at idle, the oil pressure barely registers near zero and only climbs to about halfway when the accelerator pedal is pressed.
Seeking professional advice, a call was placed to Dan Pool Mercedes in Northern Virginia. The immediate question from their service department was regarding the oil weight used in the recent service. Upon contacting the national tire and battery chain that performed the oil change, it was confirmed that 5w30 oil was used. The mechanic at Dan Pool Mercedes responded with laughter, stating that 15w40 is the appropriate oil weight for this model.
Consulting the original owner’s manual for the 1972 Benz 280SE 4.5 confirms the recommendation for “Year-round use multigrade oil, 10-w-40, 10-w-50.” This clearly indicates a discrepancy with the 5w30 oil used by the service chain. The immediate course of action is to replace the incorrect oil. The question remains: should the replacement adhere strictly to the owner’s manual recommendation of 10w-40 or 10w-50, or should the 15w40 recommendation from the Mercedes mechanic be followed? Seeking recommendations from experienced owners and mechanics familiar with the 1972 Benz 280SE 4.5 to ensure the best course of action for this classic car’s engine health.
