Oil Cooler Cap

Oil Cooler Cap

Availability: In Stock

Race tested an proven oil cooler system for the M50, S50, S52 series engines.

Design features include:

  • -8AN o-ring ports to provide a leak free fitting without the use of Teflon tape or sealant used by other oil cooler caps.

  • Viton o-rings are used throughout to maintain function and sealing in a high temperature oil environment.

  • Use of the stock filter cap bolt to reduce cost and simplify installation.

  • An internal sealing mechanism to direct oil flow through the oil cooler and through the filter.

  • 1/8" NPT side port for external oil pressure gauge.

The cap is machined from 6061-T6 billet aluminum and hard coat anodized for scratch resistance and to keep the oil cooler cap looking good for years.

To the best of our knowledge, this is the only oil cooler cap available with an actual sealing mechanism to direct the oil flow through the cooler lines and then through the oil filter.  Other cooler caps do not provide this seal and therefore the external oil coolers and lines act as a "balloon".  The lines and cooler are pressurized, but oil does not flow through them.  Flowing oil means it is being cooled and not just acting as an external reservoir.

We have run an oil cooler cap flow comparison testing with a Hedland 0-5.5 GPM flow meter.  The difference in FLOW between our oil cooler cap, the euro M3 oil filter housing, and the competition was astounding!

Recent flow testing shows that the oil cooler cap will outflow the Euro M3 Oil Filter Housing by more than 80% at the same, pressure, RPM, and oil temperature.  That is a huge difference in flow.  In the upper RPM range, there is nearly a 100% improvement in flow from the RallyRoad oil cooler cap when compared to the Euro M3 oil filter housing.  This is a worthwhile and cost effective upgrade.

Each oil cooler cap assembly also comes with a lower filter sealing ring and a new BMW MANN Oil Filter Kit.

*Kits shipped to Overseas customers now include the oil filter.
Please choose black or blue -8 AN fittings.  -10 fittings are also available.

Download Instructions


Although not necessary, we highly recommend changing your engine oil when installing the oil cooler cap and filter.

Step 1
Drain the engine oil and remove oil filter housing cap as you would during a normal oil change.

Step 2
Remove the old oil filter.

Install the filter base (aluminum disk) with o-ring facing down.  This will make a seal with the oil filter housing at the base of the supply tube.

Step 4
Install oil filter.  This oil cooler cap uses a MANN oil filter for the E46 330.

Step 5
Install the oil cooler cap using the stock oil cooler bolt.  Make sure that sealing washer is on the bolt.  Torque bolt to the factory specified 18 ft-lb.

Step 6
Install the -8 o-ring fittings to the oil cooler cap.  Fittings should be snug and flush to the cap.  Because they are o-ring fittings, they do not require as much torque as a pipe fitting to create a proper seal. Do not use Teflon tape or other sealant on the fittings as it is not required.

Step 7
Connect oil cooler lines to the oil cooler cap.  If your oil cooler and lines are secure, you are ready to start your engine.  After starting the engine for the first time, check the system for leaks.  Please pay special attention to the remaining notes at the bottom of this instruction sheet.

Note1: Your engine will require more oil than previously to maintain its proper level while also filling the extra capacity of the oil cooler and lines.  Check oil levels often to ensure proper system lubrication.

Note2: Do not install plugs into the oil cooler cap ports.  The cap is designed such that oil must flow out one port and into the other. If an oil cooler is not installed, replace the oil cooler cap with the stock cap and standard M50 oil filter.  Failure to follow this instruction may result in engine damage.