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Dodge Charger: Use the Right Oil Weight

Every police fleet manager with Dodge Chargers in their fleet knows the 5.7L HEMI® V-8 must use 5W-20 oil. Using a heavier viscosity oil will cause problems with the engine’s Multiple Displacement System, MDS (cylinder de-activation). This will produce a Diagnostic Trouble Code (DTC) and illuminate the Malfunction Indicator Light (MIL) on the dash.

The Multiple Displacement System is a complicated hydraulic, electronic and mechanical system that de-activates the hydraulic lifters on four of the eight cylinders under light loads at constant highway speeds. (The MDS is not operational at idle.) At any rate, the MDS is a tight-tolerance, oil-flow sensitive system. For the MDS lifters to correctly activate and de-activate, the 5.7L engine simply must have 5W-20, the correct weight of oil. The 5.7L engine is sensitive to this, and this maintenance fact is widely known.

Not widely known is this fact: The 3.5L V-6 in the Charger is just as sensitive to the right weight of oil! While the Owner’s Manual is emphatic about the right weight of oil in the 5.7L V-8, the Owner’s Manual is somewhat casual about the 3.5L V-6 using 10W-30. Wrong.

As an example, a certain Midwest police department has the street department change the oil in the police vehicles. Oil is oil, right? So, they put the same 15W-40 oil in the V-6 police Chargers as they put in their pickups. Hey, bulk oil is cheaper than oil in the can. Who cares if the oil cap says 10W-30? What difference can it possibly make?

Within 400 miles, both of the Chargers with the very heavy oil (15W-40 instead of 10W-30) experienced lifter noise at idle. These were brand-new vehicles. This was the very first oil change for each. Even a probationary technician could immediately identify the noise at idle, the tick, tick, tick that varied as the engine speed varied. The wrong weight of oil had caused the hydraulic lifters to fail to operate properly, even though the 3.5L V-6 is supposed to be more tolerant of oil weight than the 5.7L V-8. It is not more tolerant.

After the diagnosis and a review of the maintenance history (one oil change), the oil was immediately changed to the correct weight, 10W-30. Within 200 miles, the lifter noise went away.

The use of the right weight of oil is so important that the automakers mold it right into the oil filler cap. Ford, Dodge or Chevy…you simply must use the correct weight of oil in the police engines, even if that is not the bulk oil wherever the oil is changed. Who would have ever thought high-performance police sedans would take a different engine oil than street department and county highway vehicles?

Published in Police Fleet Manager, Sep/Oct 2009

Rating : 6.5

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