Reasons Behind Oil in Your Mini’s Coolant Reservoir

Mini Coopers are built on affordability, functionality, performance, and an extended road-range per tank of gas. While these vehicles are popular for casual car owners and high-end vehicle connoisseurs alike, they are still prone to some of the usual mechanical ailments that eventually befall vehicles. They also have their own unique mechanical failures. One of the more unusual faults that can befall a Mini Cooper is finding oil in your coolant reservoir.

The Purpose of Oil and Coolant

Your oil and coolant should never mix, as they fulfill entirely different roles and have near-opposite properties and chemical compositions. Oil is the lubricant that covers and protects all of the friction-plagued and mobile components of your vehicle’s engine. On the other hand, coolant is meant to keep your engine’s temperature steady so that everything under the hood doesn’t overheat.

If you suspect that your oil and coolant are mixing, you can check your coolant reservoir to find out. If they are mixing, you’ll notice dark brown or black splotches, or sometimes a milky-looking discoloration, floating at the top of the reservoir.

Reasons Your Oil and Coolant Are Mixing

There are several reasons that your oil and coolant may mix in your engine, and almost all of them are their own problems that will need to be fixed independently of the fluid crossover. Such issues include:

Impact from an accident

There are several reasons this can cause your oil and coolant to mix, but the math behind it is simply that high-impact accidents can cause multiple parts of the engine to crack or break. If the right components break, your oil and coolant will mix. If this is the case, the underlying broken components will need to be fixed or replaced.

Blown head gasket seal

Your head gasket is a rubber seal between the engine block and the head of your engine. Its purpose is to provide an airtight seal to maintain the high pressure the engine requires to function, as well as to keep the fluids inside from leaking out. If your head gasket is blown, the oil within your engine will leak out, and inevitably some will reach your coolant reservoir. The only recourse for a blown head gasket is to replace the head gasket, which is a costly replacement in any vehicle.

A damaged cylinder head

Your cylinders are highly-pressurized units in your engine and are major components in the combustion process that allows any car to move. If a cylinder head becomes damaged or cracked, often as a result of engine overuse, overheating, or accidental impact, air and oil will escape into the rest of the engine. Oil leaks from the cylinders often make it into the coolant reservoir.

Damage to the engine block

Damage to the engine block is not a common issue, but it is an incredibly costly replacement. The engine block is a big piece of the engine which contains several movable parts, each of which requires lubrication to function friction-freely. If your engine block itself cracks, this is likely due to driver misuse and abuse. Repeatedly overheating the engine, driving the vehicle with a lot of sudden accelerations and stops, and offroading carelessly can all lead to a cracked engine block. Once the engine block cracks, the oil inside leaks out everywhere, including into the coolant reservoir.

If you have a cracked engine block, the two options are rebuilding the engine or replacing the engine outright, both of which are expensive services that can be avoided with proper maintenance and attention to problems as they present themselves.

Nikolas Motorsport Can Help

If you think your oil and coolant are mixing, you should stop driving and have your vehicle inspected by a certified mechanic as quickly as possible, as the underlying problem itself needs to be addressed. If your oil and coolant are mixing, it’s rarely due to a minor issue, and not taking care of this problem can lead to engine malfunction. This can be incredibly dangerous, especially if it occurs while you’re in rush-hour traffic.

Nikolas Motorsport provides quality repairs & maintenance to a wide area of Bloomfield Hills, Farmington Hills, Rochester Hills, Royal Oak, Troy, and Pontiac, MI. If you suspect your Mini Cooper is experiencing problems with oil and coolant, bring it by for an inspection and diagnosis today.

* Mini Cooper S image credit goes to: Neydtstock.