GarageBoy 
To pressure test a cooling system, let the engine cool completely, take the radiator cap off, fit the correct adapter onto a coolant pressure tester, and pump the system up to the pressure printed on your radiator cap, usually 13-16 PSI. Watch the gauge for at least ten minutes. A gauge that holds means the … Read more
A low brake fluid warning light usually means the fluid in the brake fluid reservoir has dropped to the level of a float switch inside the reservoir, and the switch has closed to tell you. The usual suspects, in order of how often they turn up: worn front brake pads pulling the caliper pistons back … Read more
To check brake calipers for leaks, lift the car, take the wheel off, and look for wet fluid on the caliper body, the piston boot, the bleeder valve, and the brake hose connection, then confirm with a brake fluid level check and a pedal test. On most BMWs it takes 30 to 45 minutes per … Read more
A radiator cap is the pressure valve that seals your engine’s cooling system and holds it at a set pressure, usually 13 to 16 PSI. That pressure raises the boiling point of the coolant, and the cap also holds a vacuum on cooldown so the system stays full and free of air. When pressure climbs … Read more
Burping air out of a cooling system means circulating coolant until no air reaches the filler neck: engine at operating temperature, heater on full blast, cap off, and a steady feed going in. On a car with a conventional radiator, a clear hose clamped to the neck does most of the work. On a BMW-style … Read more
To top off coolant correctly, park the car on level ground, let the engine cool completely, then pour BMW-approved coolant of the correct specification slowly through a clean funnel into the expansion tank until the level reaches the cold MAX mark. Never open the cap on a warm engine, and never fill past MAX. The … Read more
If you have seen a mechanic or forum regular push a catch can onto your car, you probably wondered whether it is essential or just a shiny add-on. An oil catch can is a small inline reservoir that sits in your crankcase ventilation hose. It intercepts the blow-by gases on their way back to the … Read more
If your car sits for weeks at a time or only covers a few miles a week, change the oil every six months and never go past twelve, even if the odometer barely moved. Time ages engine oil faster than distance does, and the dashboard reminder will not warn you. Most of the wrong advice … Read more
Does high mileage oil work? Partly, and only for a narrow set of problems. It is an oil formulated for older engines, loaded with additives that soften aging rubber seals and add extra detergents. That can slow a weeping gasket or cut the oil an engine burns between changes. It cannot replace a worn part. … Read more
A motor oil bottle tells you three separate things: how the oil flows cold and hot, which performance tests it passed, and whether a specific carmaker licensed it. If you know how to read oil bottle labels and certifications, you can match any jug to your owner’s manual in about a minute and stop guessing … Read more