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Bmw 135Is Engine Oil Thermostats

Bmw 135Is Engine oil thermostats

Starting at $141.95, AutoBuffy stocks 1 engine oil thermostats from URO for the Bmw 135Is. The oil thermostat regulates oil flow through the cooler, keeping oil at the temperature range where it protects best. When it fails, oil runs too cold or too hot, accelerating wear and risking engine damage.

Signs your Bmw 135Is needs a new engine oil thermostat

  • Oil temperature gauge reads consistently lower than normal, even after a full warm-up cycle
  • Oil temperature spikes higher than usual under load or in stop-and-go traffic
  • Visible oil sludge or milky discoloration on the dipstick or oil cap, indicating thermal cycling issues
  • Oil cooler lines running abnormally cold to the touch when the engine is fully warmed
  • Check Engine or oil temperature warning light illuminates without another obvious cause
  • Frequent need to change oil earlier than your normal interval due to rapid oil degradation

Which engine oil thermostat should you buy for your Bmw 135Is?

The main decision is whether to match the OE opening temperature rating or choose an aftermarket unit with a slightly different calibration for your driving conditions. Fit and material quality matter most here — a thermostat that sticks open or closed causes immediate lubrication problems. Check your Bmw 135Is's specific cooler circuit design (integrated housing vs. inline) before ordering.

OE-Equivalent Replacement
Best for
Daily drivers, warranty-conscious owners
What you get
Matches factory opening temperature and flow rate exactly; drop-in fit with no calibration guesswork
OEM / Dealer-Sourced Unit
Best for
Owners who want the original part number match
What you get
Guaranteed fitment and factory materials; typically the highest upfront cost but lowest comeback risk
High-Performance / Lower-Temp Aftermarket
Best for
Towing, track use, or hot climates
What you get
Opens earlier to route oil through the cooler sooner; reduces peak oil temps under heavy load
Housing-Integrated Kit (thermostat + housing)
Best for
Vehicles with cracked or corroded housings
What you get
Replaces both the thermostat and its plastic or aluminum housing together; eliminates a second failure point

Engine oil thermostats brands we stock for your Bmw 135Is

URO
1 option · from $141.95

Replacing the engine oil thermostat on a Bmw 135Is

Moderate⏱ 1–2 hoursSocket set and ratchetTorque wrenchOil drain panPick or small flathead screwdriver (for O-ring removal)Clean lint-free rags

Drain or isolate the oil from the cooler circuit, then unbolt the thermostat housing and remove the old thermostat and its O-ring or gasket. Install the new thermostat with a fresh O-ring, reassemble the housing, and torque the fasteners to the manufacturer's specification for your Bmw 135Is. Refill or top off the oil, start the engine, and verify oil temperature returns to the normal operating range before returning the vehicle to service.

Frequently asked questions

How much does it cost to replace engine oil thermostats on a Bmw 135Is?
Parts start at $141.95 at AutoBuffy for the Bmw 135Is. A shop will typically add one to two hours of labor on top of the part cost. Total repair cost varies by whether the housing needs replacement and how accessible the thermostat is in your specific engine layout.
What happens if I drive my Bmw 135Is with a failed engine oil thermostat?
A stuck-open thermostat keeps oil too cold, preventing it from reaching proper viscosity and leaving engine surfaces under-lubricated. A stuck-closed thermostat blocks flow to the cooler, causing oil to overheat and break down rapidly. Either condition accelerates bearing, piston, and cam wear and can lead to costly engine damage if ignored.
How long does an engine oil thermostat last on a Bmw 135Is?
Most oil thermostats last many years under normal driving conditions, often well beyond 100,000 miles. Failure rates increase in vehicles that experience frequent overheating events, extended idle periods, or infrequent oil changes, all of which degrade the wax element or valve seal inside the thermostat over time.
Is an engine oil thermostat the same as a coolant thermostat on a Bmw 135Is?
No. The coolant thermostat regulates engine coolant temperature in the water circuit. The engine oil thermostat is a separate valve in the oil circuit that controls whether oil bypasses or flows through the oil cooler. Some engines have both; replacing one does not address a problem with the other.
Can I remove the engine oil thermostat and run without one on my Bmw 135Is?
Removing it is not recommended. Without the thermostat, oil continuously circulates through the cooler regardless of temperature. In cold climates this keeps oil below its optimal operating temperature for most of a short trip, increasing wear. In hot climates the unregulated flow may still be insufficient to prevent overheating under load.
Do I need to flush the oil system after replacing the engine oil thermostat on a Bmw 135Is?
If the old thermostat failed due to sludge contamination or caused oil overheating, an oil flush and fresh oil change at the same time is strongly advised. Otherwise a standard oil change concurrent with the repair is sufficient to remove any debris disturbed during the job and protect the new thermostat from day one.

Shop engine oil thermostats by year for the Bmw 135Is

2013

More parts for your Bmw 135Is

Vehicle BatteryWheel Bearing & Hub SetEngine Oil FilterSeat Belt Buckle Button StopEngine Coolant Bleeder ScrewEngine Coolant Thermostat Housing AssemblyAccelerator Pedal SensorElectric Engine Water Pump

Engine oil thermostats for other Bmw models

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