CSF Performance Oil Cooler 2011–2016 BMW 135i(X) 5 Door F20 / M135i(X) 3 Door F21This oil cooler from CSF Performance features an innovative 2 core in series design that gives you 5 additional cooling rows for a 40 percent increase in heat rejection. The cooler core is made with CSF Performance's AC condenser technology which uses a 1 row super high pressure 26mm multi channel microtube for optimal oil flow. This is a drop in unit that requires no modifications to install and accepts all OEM connections, brackets and ducting.