Failure mode - Ram ProMaster 3.6L Pentastar V6 (2014-2025)

Plastic oil filter/coolant housing-adapter leak (the signature Pentastar leak)

Reliability tier: aggregated - verify before ordering, see /disclosure/

Symptoms

oil film tracking down the back of the engine onto the transmission bellhousing (routinely misdiagnosed as a rear main seal)
coolant loss alongside the oil leak (the housing carries both circuits)
oil level drops between services with no obvious pan drip

Compare with the other causes of the same sign on this engine: losing coolant (2 causes) · oil leak, oil consumption or rising oil level

Root cause

The 3.6 Pentastar's oil filter adapter / oil cooler housing is plastic and lives deep in the valley; it cracks or weeps at its seals and leaks oil, coolant or both. Over-torqued oil-filter caps from quick-lube services are a classic trigger. The standard fix is the updated (often aluminum aftermarket) housing with fresh gaskets and o-rings. NHTSA VOQ is thin on it (owner complaints file as generic 'oil leak') - the service literature and the repair-community consensus carry the record, LML-wave pattern.

Diagnosis

degrease and observe: oil tracked to the bellhousing from the valley = the housing, not the rear main
pressurize the cooling system and watch for coolant weep at the housing
on replacement: correct torque and alignment - installation errors restart the leak

Fixes

housing-adapter replacement (updated/aluminum housing) with gaskets and o-rings ()

Prevalence

very-common