Use the Tech Tips links below to learn some interesting tips, shortcuts, or special things to watch out for when owning and servicing your BMW automobile. Simple advice from our experts that you can use to take better care of your BMW. Check back often as this page is being updated frequently! 

Sludge Monster
Safely Jump Starting your BMW
BMW Model Codes
BMW Engine Codes
Heel/Toe Downshift

We've all probably seen an engine that's been consumed by the "sludge monster". It's not a pretty sight and has been the cause of death of many engines. The first clue that an engine has been inhabited by the sludge monster usually becomes evident during an oil change (when the thick goo dribbles out the oil pan drain hole or nothing at all comes out). We usually identify the fatal cases of sludge monster victims after the vehicle arrives at the shop under the auxiliary power of a tow truck.

Contaminants are deadly enemies of an engine. They enter with the air flow and are also generated by the friction of metal against metal. These facts may astound you: for every 100 gallons of gasoline burned in an engine, the following by-products are produced:

     90 to 120 gallons of water
     3 to 10 gallons of unburned gasoline
     1/2 to 3 pounds of soot and carbon
     1/4 to 1 pound of varnish
     1 to 4 pounds of sulfuric and nitric acid

A measurable percentage of these by-products ends up in the motor oil. Detergents and dispersants in the oil must be able to keep most of these con-taminants neutralized or suspended in the oil as microscopic particles so they don't form sludge, damaging deposits and corrosion. When the waste materials are dispersed properly in the oil, the filter can trap the larger particles. During an oil change, the contaminants too small to be filtered are re-moved with the engine oil. It's important to note here that good air filters and good oil filters trap more contaminants than lesser quality filters, making the oil's job easier.

Sludge formation begins when the chemically suspended particles of contaminants begin to settle out of the oil. It's a fairly daunting task for engine oil to suspend all the contaminants thrown at it, and any engine oil can do this successfully to a point. Amsoil, and some other quality synthetic motor oils, are able to perform this task more effectively and for longer periods of time. But eventually, if the oil is not changed often enough, a "breaking point" will be reached. This breaking point is either when there are too many contaminants to handle or when the oil's chemical defenses are weakened, and it is caused by two main things: excessive accumulation of contaminants in the oil and chemical changes in the makeup of the oil itself (depletion of the additives and oxidation).

As more particles are suspended, less of the additives are available to do their job. Knowing this makes it easy to see why too much time between oil changes can be one cause of the oil reaching its "breaking point".

The sludge monster's invitation can be repeatedly rejected. To keep the sludge monster looking for a dinner date in someone else's engine, use a quality fully synthetic oil in recommended viscosity and change it at recommended intervals.

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"Jump starting" should be avoided if possible because of damage that can occur to various electrical components. The electronics found throughout our cars can handle voltages up to 15v but only briefly. Jump starting equipment found on some tow trucks can operate anywhere from 18 to 24 volts. Damage to certain electrical components is assured if this equipment is used.
However, in certain circumstances, jump starting may not be avoidable. To protect the electrical components in your car, follow the procedure described below. 

• Make sure that neither of the vehicles involved are touching (on certain vehicles, ground points may exist on bumpers).
• Ensure that both vehicles have batteries of the same voltage and are approximately the same size/strength to ensure sufficient power for jump starting.
• Carefully observing polarity, connect the positive jumper cable to the battery's Positive Junction Post (or battery positive terminal, if the vehicle is not equipped with a battery's Positive Junction Post) of the vehicle to be jumped started and then the battery positive terminal of the vehicle being used to jump start. (See below for picture of Junction Post)
• Next connect the dead car's negative jumper cable to a CHASSIS GROUND (i.e.. Bolt at front shock absorber upper mount) on both vehicles. At this point, connect the last cable, the negative for the jumping car to a CHASSIS GROUND. Doing so avoids any potential arcing of battery gases, which could cause an explosion.
• Jump start the dead vehicle by turning the key as usual. For the first attempt, leave the jumping car off.
• If the car doesn't start on first attempt, start the jumping car and leave it running. Wait a few minutes before the 2nd attempt. If it still will not jump start, odds are your battery is completely dead. In this case, contact us to have your vehicle towed in so we can thoroughly check the charging system and fix the problem.
• If the dead car successfully starts, before disconnecting the jumper cables, switch on the heater fan to the highest speed, the rear window defroster and your low beam headlights. This helps minimize voltage spikes when disconnecting the cables.

• Disconnect the negative cable on jumping car first, then the negative on the formerly dead car. Next, disconnect the positive cables in either order. Disconnecting the cables in this order ensures that any momentary arcing that may occur is away from the battery (in the case of vehicles with the battery in the engine compartment) and any gases produced by the battery. To prevent future problems, it is recommended that you schedule an appointment to have your battery load tested and your charging system inspected.  

Failure to follow this procedure exactly may result in expensive damage to your vehicle's sensitive electronics. 

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BMW model codes help you to identify your car in the language that the manufacturer uses (no, not German!). Using the codes lets you order parts and accessories with confidence. For example E39 is a 5-series body from 1996 while E46 is a 3-series body from 98-on.
 

E Code	Model Series	Model Years
E3	2500, 2800, Bavaria, 3.0s/si	1968-1977
E6	1600, 1800, 2000 Touring	1973-1975
E9	2500cs, 2800cs, 3.0cs	1965-1975
E10	2002, 2002tii	1968-1975
E10C	2002 Convertible	1971
E10T	2002 Turbo	1973-1975
E12	5 Series	1973-1981
E12/1	5 Series Facelift	1977-1981
E12/1S	M Series (M535i)	1980-1981
E20	2002 Turbo	1973-1975
E21	3 Series	1977-1983
E21/1	3 Series Facelift	1978-1979
E21/2	3 Series Facelift	1979-1984
E23	7 Series	1978-1988
E23/1	7 Series Facelift	1979-1982
E23/2	7 Series Facelift	1982-1986
E24	6 Series	1978-1988
E24/2	6 Series Facelift	1988-1989
E24/1S	M Series (M635csi)	1984-1987
E24/2S	M Series (M6)	1988-1989
E25	Turbo	1972
E26	M1	1979-1981
E28	5 Series	1982-1988
E28S	M Series (M5)	1985-1988
E30	3 Series	1984-1992
E30/2	3 Series Coupe	1984-1992
E30/2C	3 Series Convertible	1986-1992
E30/2S	M Series (M3)	1987-1991
E30/2SC	M Series (M3) Convertible	1988-1991
E30/4	3 Series Sedan	1984-1991
E30/5	3 Series Touring	1998-1992
E30/16	3 Series 4WD (325iX)	1986-1991
E30/88	3 Series Facelift	1998-1991
E30Z	Z1	1989-1990
E31	8 Series	1990-1999
E31S	850CSi	1991-1999
E32	7 Series	1988-1994
E32/2	7 Series Longbase	1988-1994
E34	5 Series	1989-1996
E34/5	5 Series Touring	1991-1996
E34/16	5 Series Touring 4WD	1992-1996
E36	3 Series	1992-1999
E36/2	3 Series Coupe	1992-1999
E36/2S	M Series (M3) Coupe	1992-1999
E36/2C	3 Series Convertible	1993-2000
E36/2CS	M Series (M3) Convertible	Unknown
E36/3	3 Series Touring	1996-1999
E36/4	3 Series Sedan	1992-1999
E36/4S	M Series (M3) Sedan	1995-1998
E36/5	3 Series Compact	1995-1999
E36/7	Z Series (Z3 Roadster)	1996-2002
E36/7S	M Series (M Roadster)	1998-2002
E36/8	Z Series (Z3 Coupe)	1998-2002
E36/8S	M Series (M Coupe)	1998-2002
E38	7 Series	1995-2002
E38/2	7 Series Longbase	1995-2002
E38/L7	7 Series Limousine	1999-2002
E39	5 Series	1997-2003
E39S	M Series (M5)	1997-2003
E46	3 Series	1999-Current
E46/2	3 Series Coupe	1999-Current
E46/2C	3 Series Convertible	2000-Current
E52	Z Series (Z8)	2000-2002
E53	X Series (X5)	2000-Current
E60	5 Series Sedan	2003-Current
E61	5 Series Touring	Not Available
E63	6 Series	2004-Current
E65	7 Series	2002-Current
E66	7 Series	2002-Current
E83	X Series (X3)	Not Available
E85	Z Series (Z4)	2002-Current

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Ever wonder what engine code your BMW uses?  These are the current codes used.

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The heel-toe downshift is a fundamental technique to driving fast through corners. During a heel-toe downshift, you'll be steering with the left hand, shifting with the right hand, clutching with the left foot, and working both the brake and gas pedals with the right foot -- all at exactly the same time.

 

The downshift begins with a full throttle acceleration towards a corner.

 

Lift the right foot from the gas pedal and press the brake pedal.

 

Just before the braking is done, the left foot depresses the clutch pedal.

The right hand begins the downshift.

The right foot is still applying, but easing up on the brake pressure as the car approaches the turn-in, then the foot rotates so the heel is above the corner of the gas pedal.

As the shift passes through neutral, the right heel gives a quick push of the gas pedal to rev the engine quickly (the ball of the foot is still on the brake easing up even more).

 

The left foot releases the clutch, the right foot rotates off the gas. Done correctly the RPMs generated by the throttle blip above matches the RPMs needed, and as the clutch is released the engine engages smoothly with the current wheel speed. There should be no forward or braking lurch when the clutch is let go.

 

The right foot completes the braking with a smooth release.

 

The right foot moves over to the gas pedal to assume the normal position at first only to maintain the pressure needed to sustain the vehicle speed throught the first part of the corner. Then pressure is gradually applied to accelerate out of the turn.

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