Brake Fluid

[Napes]

Pep Boys, in Southern Arizona, carried Castrol LMA until a few months ago - but no more. I just flushed the fluid in my wife's '76 yesterday and used Valvoline Synthetic Dot 3 & 4 Brake Fluid. It is slightly more hydroscopic than Castrol, but even in the dead of winter down here our humidity today was 15%. In a couple of months we'll have 4-5% each day, so I'm not real worried about water in the fluid.

Besides, I flush every 12-18 months anyway.

Bob Napier

[Simeon]

But Snakedriver, you never hit the brakes, just the skinny pedal.

Keeps the corrosion down

Snakedriver

Do you out run it?

[c.d.iesel]

ya cant go wrong with BMW spec brake fluid -

online or any dealer

then flush ( brakes and clutch! ) every year

and what BmW says about your brake fluid:

1.0 General Information

Brake fluid, (glycol-based) as used in BMW brake systems, must conform with the following requirements:

— High boiling point

— Good low temperature resistance

— Low compressibility

— Corrosion inhibition for all metal parts inside of brake system

— Compatibility with all rubber parts used in brake system

These requirements are fulfilled by reputable brand name DOT 4 brake fluids.

Silicone-based brake fluid has better compressibility, but because it cannot absorb moisture, is subject to vapor lock

attemperatures above 212°F/ 100°C. At lower temperatures, it may even ice-up. Silicone-based brake fluid is not

approved by BMW.

Glycol-based brake fluid absorbs moisture from the atmosphere (hygroscopicity) through the brake fluid reservoir, brake

hoses, etc. This absorption of water lowers the original boiling point of brake fluid and active safety of the entire system.

If there is extended use of the brakes while driving downhill at high speeds, the thermal loads could cause vapor bubbles

in the brake fluid. This situation could lead to reduced braking effectiveness.

The original boiling point of factory-approved brake fluids is approximately 500°F/260°C. Due to the hygroscopic behavior

of brake fluid, 2% of water within one year is permissible. The boiling point of brake fluid will drop by 100°C with 3% water

absorption. It is essential to conform with brake fluid changing intervals in order to guarantee the safety and maximum

effectiveness of a brake system.

It would not be sufficient simply to replace the brake fluid in the reservoir. Experience has shown that vapor bubbles will

occur first on areas of the brake caliper. This area is subjected to high thermal loads and also exposed to heat

transmission.

When replacing the brake fluid, the brake fluid used as the working fluid in the hydraulic clutch should also be replaced.

This is done by draining the clutch operation system or bleeding with the help of the clutch slave cylinder.

The brake fluid should be replaced by filling the brake fluid reservoir. Make sure that each bleeder valve of all wheel

cylinders or brake calipers is kept open until the escaping brake fluid is clear and without air bubbles. Never use brake

fluid that has been drained from the system.

Storage of brake fluids also deserves your special attention. The aging process begins with the initial contact between the

brake fluid and the atmosphere. This means immediately after a new container is opened.

To keep the boiling point of stored brake fluids as high as possible, we recommend conforming with the following points:

— Close all containers tightly.

— Select small size containers, which can be used up quickly.

— Avoid pouring contents of one container into a different container.

Page 2 of 2

2.0 Handling Brake Fluids

Brake fluids could be mixed up accidentally with mineral oil products so it is important to leave them in their original

containers and not pour them into a different container.

Caution

If brake fluid accidentally comes into contact with your skin, wash it off with soap and water immediately. Eyes should be

thoroughly flushed with cold water if contacted by brake fluid. Vomiting should be induced if brake fluid is internally

consumed and a physician should be consulted.

If brake fluid is spilled or drips on a painted surface, wash it off with water immediately to prevent damage to the paint

finish. Never rub it off. Brake fluids should not have contact with grease or oil. Wash hands to remove grease and oil

before working with brake fluids. Also make sure that grease cannot enter the brake system.

Drained brake fluid must never be discarded in the garbage, oil disposal tanks or water drains.

Read instructions on container label prior to use.

3.0 BMW Tested And Approved Brake Fluids

BMW Tested and Approved DOT 4 ESL Brake Fluid is available as follows:

12 fl. oz. bottle BMW Part No. 81 22 0 142 156

1 gallon container BMW Part No. 81 22 0 142 155

See S.I. Bulletin B 34 09 01.

4.0 Brake Fluid Change Intervals

All Models Brake fluid change interval every 2 years.

[Miked2002]

Hi C.D.

Thanks for the great info.

[TobyB]

ya cant go wrong with BMW spec brake fluid -

No, but you can go broke trying to pay for it.

I even race an E30 with GT LMA. Here, Action (now Baxter's) carried it

at least a few months ago.

And my experience with Dot 5 was that it was MORE compressible, and

had terrible lubricity, leading to a pedal feel that I hated.

So I dumped it.

t

[lilmo]

ya cant go wrong with BMW spec brake fluid -

online or any dealer

then flush ( brakes and clutch! ) every year

and what BmW says about your brake fluid:

1.0 General Information

Brake fluid, (glycol-based) as used in BMW brake systems, must conform with the following requirements:

— High boiling point

— Good low temperature resistance

— Low compressibility

— Corrosion inhibition for all metal parts inside of brake system

— Compatibility with all rubber parts used in brake system

These requirements are fulfilled by reputable brand name DOT 4 brake fluids.

Silicone-based brake fluid has better compressibility, but because it cannot absorb moisture, is subject to vapor lock

attemperatures above 212°F/ 100°C. At lower temperatures, it may even ice-up. Silicone-based brake fluid is not

approved by BMW.

Glycol-based brake fluid absorbs moisture from the atmosphere (hygroscopicity) through the brake fluid reservoir, brake

hoses, etc. This absorption of water lowers the original boiling point of brake fluid and active safety of the entire system.

If there is extended use of the brakes while driving downhill at high speeds, the thermal loads could cause vapor bubbles

in the brake fluid. This situation could lead to reduced braking effectiveness.

The original boiling point of factory-approved brake fluids is approximately 500°F/260°C. Due to the hygroscopic behavior

of brake fluid, 2% of water within one year is permissible. The boiling point of brake fluid will drop by 100°C with 3% water

absorption. It is essential to conform with brake fluid changing intervals in order to guarantee the safety and maximum

effectiveness of a brake system.

It would not be sufficient simply to replace the brake fluid in the reservoir. Experience has shown that vapor bubbles will

occur first on areas of the brake caliper. This area is subjected to high thermal loads and also exposed to heat

transmission.

When replacing the brake fluid, the brake fluid used as the working fluid in the hydraulic clutch should also be replaced.

This is done by draining the clutch operation system or bleeding with the help of the clutch slave cylinder.

The brake fluid should be replaced by filling the brake fluid reservoir. Make sure that each bleeder valve of all wheel

cylinders or brake calipers is kept open until the escaping brake fluid is clear and without air bubbles. Never use brake

fluid that has been drained from the system.

Storage of brake fluids also deserves your special attention. The aging process begins with the initial contact between the

brake fluid and the atmosphere. This means immediately after a new container is opened.

To keep the boiling point of stored brake fluids as high as possible, we recommend conforming with the following points:

— Close all containers tightly.

— Select small size containers, which can be used up quickly.

— Avoid pouring contents of one container into a different container.

Page 2 of 2

2.0 Handling Brake Fluids

Brake fluids could be mixed up accidentally with mineral oil products so it is important to leave them in their original

containers and not pour them into a different container.

Caution

If brake fluid accidentally comes into contact with your skin, wash it off with soap and water immediately. Eyes should be

thoroughly flushed with cold water if contacted by brake fluid. Vomiting should be induced if brake fluid is internally

consumed and a physician should be consulted.

If brake fluid is spilled or drips on a painted surface, wash it off with water immediately to prevent damage to the paint

finish. Never rub it off. Brake fluids should not have contact with grease or oil. Wash hands to remove grease and oil

before working with brake fluids. Also make sure that grease cannot enter the brake system.

Drained brake fluid must never be discarded in the garbage, oil disposal tanks or water drains.

Read instructions on container label prior to use.

3.0 BMW Tested And Approved Brake Fluids

BMW Tested and Approved DOT 4 ESL Brake Fluid is available as follows:

12 fl. oz. bottle BMW Part No. 81 22 0 142 156

1 gallon container BMW Part No. 81 22 0 142 155

See S.I. Bulletin B 34 09 01.

4.0 Brake Fluid Change Intervals

All Models Brake fluid change interval every 2 years.

BMW stuff $4.50/12 oz. via Amazon right now. That's about $13.50/liter. Think I may stock up.

[roadhog0]

I use the Prestone in the yellow bottle in every rig I own. Been in the BMW for at least two years now and have no problems with it. I also run it in my pickup truck. My parents run it in all their rigs as well.