Race Oil Thermostat Bypass — M156 PRE 2012 MODEL

Permanently open oil thermostat engineered for Mercedes M156 pre 2012 engines. Always-open design routes oil continuously to the cooler for maximum flow and lower oil temperatures during sustained or spirited driving — ideal for track-focused use where minimising peak oil temps matters most.

Key features:

Permanently open — no moving parts, zero flow restriction
Direct-fit for M156 PRE 2012 models oil thermostat housings (vehicle-specific fit required)
CNC-machined aluminum construction with corrosion-resistant finish
Lightweight, durable design built for high-temp environments

Performance benefits:

Immediate, unrestricted oil flow to external coolers — reduces peak oil temps under high load
Lowers risk of oil viscosity breakdown and thermal-related wear on track or spirited runs
Eliminates thermostat failure (no sticking/partial opening)

Trade-offs / considerations:

Slower oil warm-up after cold starts and during low-load driving — oil reaches operating temp later
Oil will run cooler than stock at normal driving
Intended for race/track use, not optimal for owners prioritising rapid warm-up or strict emissions operation

Fitment note — M156 vs M159:

This product fits M156 and M159 engines, but some M156 cars were originally equipped with the M159-style thermostat housing/part number. Customers must confirm which thermostat type is fitted to their vehicle (M156 or M159) and select the matching part —verify by checking your car’s OEM part number or comparing the existing thermostat housing before ordering.

Recommended use:

Track days, racing, high-performance/spirited driving and builds with large oil coolers
Warmer countries
Not recommended as a permanent daily-driver replacement if rapid oil warm-up or factory temperature ranges are required as such in colder countries

Installation notes:

Direct-replacement design. May require new O-ring.
Verify vehicle-specific fitment, orientation, and part number (M156 vs M159) before installation
After installation, monitor oil temperature and level; use a temp gauge to confirm operating range