Light will not go off

Your vehicle may be equipped with low oil pressure engine protection. If so, that issue may need addressed first. Low oil pressure sw cuts off fuel pump, saving engine from catastrophic failure.

If the oil pressure is otherwise normal except when you are running at higher speeds i suspect the relief valve on the oil pump is sticking in the open or partially open position at constant higher engine speeds.

You will need to have the oil pressure on the engine properly tested by a professional and the cause of the low oil pressure diagnosed. If you drive the car on low oil pressure you will cause very expensive internal engine damage many multiple times the cost of fixing the current problem.

Insufficient engine oil changes for the type of vehicle use (a practice which most owners follow because they usually do the absolute minimum thinking they will save money) causes sludge build up in the engine and these kinds of issues that you have now. Most owners are even too lazy to routinely and frequently check under bonnet fluid levels between services - engine oil level, coolant level, power steering fluid level etc.

That depends on the type of oil warning light being displayed. There are 2 types of warning lights

1. Low oil pressure light which all cars have
2. low oil level light which some cars have.

Low OIL PRESSURE warning means the oil pressure is below minimum and when this happens there will be insufficient lubrication of many engine parts because sufficient oil cannot get to all parts of the engine it is required to lubricate. Until the cause is identified and rectified the warning light will remain. If you run your engine with low oil pressure you will cause expensive damage to internal engine components.

Low OIL LEVEL warning means the oil in the sump has dropped to a dangerously low level (which may be due to an oil leak or abnormal oil consumption by the engine.) This warning means the oil level needs to be topped up and the warning will stay displayed until you top up the oil. Running the engine with low oil will cause expensive engine damage.
Since it is a 2 minute job, Oil levels should be checked fortnightly as a minimum, together with radiator coolant and power steering fluid levels, if you run the car most days each week as most people do.

It is possible for a warning light to remain displayed when the cause has been dealt with because there is a problem with the sender unit. However it needs to be established with alternative checks that the problem has been fixed before investigating if there is a problem with the warning light itself.

Brake Light. Make sure you are not driving with hand brake on. Check brake-fluid level. Top off brake fluid if low and make appointment to check brakes. Driving with brake light can be dangerous; deal with this soon. Call tow truck or drive carefully and slowly to shop.
ABS (antilock brake system) Light. Indicates either low brake-fluid level, stuck brake caliper or faulty ABS. Check brake fluid and make appointment to get brakes checked. Call tow truck or drive carefully and slowly to shop.
Oil Light. Either engine is very low on oil or there is no oil pressure. Pull over and turn off engine immediately. Check oil level and add oil if low. Turn engine back on to see if light has gone off. If oil light is still on, bad oil pump (no oil pressure) is likely. Call tow truck.
Check Engine Light. Car's computer senses engine problem. Difference in performance may not be noticeable, but make appointment to have car diagnosed. This usually cost around $65-$75 to do. OK to drive. If problem is serious, computer may switch to limp-home (low-power) mode and you won't have option of waiting to bring car into shop.
Air Bag Light. Get air bags checked. Problem could prevent them from activating in accident. OK to drive, but not safe in accident.
Battery Charge Light. Alternator is not charging. OK to drive, but turn off any unneeded electrical devices (radio, heater, defroster) and avoid starting engine more than necessary. Bring car into shop soon to avoid getting stranded. When alternator is not charging, battery loses charge and car stops working.
Emissions Lights (O2 sensor, EGR, check emissions). Depending on car model, these lights may indicate problem with emissions sensor or may light up at certain mileage, usually 60,000 miles (100,000 km). Get sensors checked. OK to drive. If problem exists, car might get poor gas mileage.
OBD Tools 365 Days Shop

The rear seal of the engine could have started to leak but a loose oil pan or damaged oil filter could be a factor.

The low washer fluid light could be the sensor in the tank, and the low tire pressure could be a problem with the ABS system.
Check your owners manual on resetting the tire pressure light.

It is the same for any mercedes. here is a copy from another source on the internet

Interior
· Function check
· Check warning and indicator lamps, illumination and interior lighting
· Check windshield wiper, windshield washer system, headlamp cleaning system
· Reset maintenance service counter in instrument cluster

Wheels, brakes
· Check front brake pads for lining thickness
· Check tires for damage, condition
· Correct tire inflation pressure

Engine compartment
· Change engine oil and filter
· Fluid level checks of the following:
· Engine cooling system, antifreeze and corrosion protection
· Windshield washer system
· Brake system
· Check and correct battery fluid level
· Check battery condition
· Check catch, safety catch and hinges on engine hood for proper operation

Trunk
· Correct tire inflation pressure in spare tire
· Check battery condition

Just change the oil/filter.You may of set off low oil indicator.After change if check engine light is still on.Have local parts store check diagnostic codes

Because of changing outside temps this happens, just hold reset button on left side of dash until it reads tire pressure 100% again, just make sure your pressure is right before you do it. this is the same for oil changes and the like.

A-Service — First visit at approximately 10,000 miles or 1 year, but determined by Flexible Service System; then every 20,000 miles or 2 years.
Interior
· Function check
· Check warning and indicator lamps, illumination and interior lighting
· Check windshield wiper, windshield washer system, headlamp cleaning system
· Reset maintenance service counter in instrument cluster

Wheels, brakes
· Check front brake pads for lining thickness
· Check tires for damage, condition
· Correct tire inflation pressure

Engine compartment
· Change engine oil and filter
· Fluid level checks of the following:
· Engine cooling system, antifreeze and corrosion protection
· Windshield washer system
· Brake system
· Check and correct battery fluid level
· Check battery condition
· Check catch, safety catch and hinges on engine hood for proper operation
Trunk
· Correct tire inflation pressure in spare tire
· Check battery condition

B-Service — First visit at approximately 20,000 miles or one year after previous service, but determined by Flexible Service System; then every 20,000 miles or 2 years.
Services performed:

Interior
· Function check
· Check warning and indicator lamps, illumination and interior lighting
· Check windshield wiper, windshield washer system, headlamp cleaning system
· Reset maintenance service counter in instrument cluster
· Replace dust filter (not applicable to SL-Class)
· Replace combination filter (SL-Class)
· Check parking brake (function test only)

Wheels, brakes
· Check condition/thickness of front and rear brake discs
· Check front and rear brake pads for lining thickness
· Check tires for damage and condition
· Measure tread depth, record in mm
· Correct tire inflation pressure

Underside of Vehicle
· Check for major components leakage
· Check for chafe marks, line routing, damaged components
· Check condition of front axle ball joints and rubber boots
· Check condition of mechanical steering components and rubber boots

Engine Compartment
· Check for major components leakage
· Check for chafe marks, line routing, damaged components
· Check and replenish all fluid levels
· Change engine oil and filter
· Check engine cooling system, antifreeze and corrosion protection
· Check brake system
· Check power steering
· Check Active Body Control
· Check windshield washer system
· Check and correct battery fluid level
· Check battery condition
· Check catch, safety catch and hinges on engine hood for proper operation
· Check condition of poly V-belt

Trunk
· Check battery condition
· Correct tire inflation pressure in spare tire