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Bosch WR9LS Spark Plug
| Brand | Bosch WR9LS |
|---|---|
| Center Electrode Core Material | Silver |
| Center Electrode Tip Material | Silver |
| Ground Configuration | Standard |
| Ground Electrode Quantity | 1 |
| Ground Electrode Tip Design | Standard |
| Ground Electrode Tip Material | Nickel-Chromium |
| Hex Size | 20.8 |
| Insulator Material | Ceramic |
| Insulator Type | Projected |
| Manufacturer Heat Range | 9 |
| Outdoor Power Equipment Application | No |
| Package Contents | Spark Plug |
| Pre-Gap Size | .7 |
| Reach | 9.5 |
| Resistance | 6000 |
| Resistor | Yes |
| Seat Type | Flat |
| Short Style | No |
| Spark Plug Type | 4-Cycle |
| Thread Diameter | 14 |
| Product line | Silver |
| Fits | BMW · 26 vehicles |
Silver alloy tip. Helps resist electrode wear and improve spark plug efficiency.
Resistor design. Supports cleaner ignition performance in a 4-cycle spark plug.
Projected insulator. Promotes efficient combustion chamber performance.
Will it fit your vehicle?
Free return shipping if it doesn't fit.
Bosch Silver WR9LS Spark Plug for BMW Applications
The Bosch Silver WR9LS spark plug is built for older European performance engines that run at elevated combustion chamber temperatures. Its silver-alloy center electrode tip is used to reduce electrode wear and maintain efficient spark delivery in demanding ignition systems.
Key Features
- Silver center electrode tip and silver core material for improved wear resistance
- Resistor spark plug with 6000 resistance for secondary ignition noise control
- Projected ceramic insulator for stable combustion chamber exposure
- Standard ground electrode design with nickel-chromium tip material
- Preset .7 gap; do not gap before installation
- Flat seat, 14 mm thread diameter, 9.5 mm reach, and 20.8 mm hex size
- Manufacturer heat range 9 for older European performance applications
Product Details
Bosch Silver WR9LS is a 4-cycle spark plug engineered around the needs of older BMW engines that operate at higher temperatures and place added stress on the electrodes. The silver alloy center electrode helps resist wear, while the projected ceramic design supports consistent spark exposure in the combustion chamber. This part number, WR9LS, is listed for select BMW 325e, 325es, 528e, 533i, 535i, 535is, 535i, 635CSi, and 735i applications, making it a direct-match ignition service part for specific vintage European vehicles.
Bosch Silver is the product line for applications where electrode durability and stable ignition performance matter in higher-heat operating conditions. For BMW owners maintaining original-style ignition service on older performance models, WR9LS provides the correct plug design and preset gap specification for the listed applications.
This part cross-references Bosch WR9LS for the same application.
What It Helps Address
- Misfire caused by worn spark plug electrodes
- Hard starting from weak or inconsistent spark output
- Rough idle related to aged ignition components
- Reduced combustion efficiency in high-temperature engines
- Ignition noise in resistor-equipped secondary ignition systems
Installation Notes and Tips
- Install only on the listed BMW applications and verify year-specific fitment before service.
- Do not gap this plug; the gap is preset from the factory.
- Use the correct 14 mm spark plug socket and confirm the flat seat style matches the cylinder head.
- Inspect ignition wires, distributor components, and coil condition during spark plug replacement.
- Follow the vehicle service manual for torque and service interval guidance.
Quality Assurance
Bosch manufactures this spark plug for specific older European performance applications, using silver-alloy electrode materials to address the heat and wear demands found in those engines. WR9LS is built to the stated Bosch specifications for the listed BMW fitments.
- Fits 1985-1989 BMW 635CSi, N/A
- Fits 1988 BMW 535i, N/A
- Fits 1988 BMW 535is, N/A
- Fits 1984-1987 BMW 325e, N/A
- Fits 1986-1987 BMW 325es, N/A
- Fits 1987 BMW 528e, N/A
- Fits 1985-1987 BMW 535i, N/A
- Fits 1982-1986 BMW 528e, N/A
- Fits 1985-1986 BMW 735i, N/A
- Fits 1983-1984 BMW 533i, N/A
| Year | Make | Model | Liters | Cylinders | Position | Notes |
|---|---|---|---|---|---|---|
| 1989 | BMW | 635CSi | 3.5L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1988 | BMW | 535i | 3.5L | L6 | N/A | Do Not Gap, Gap is Preset; Early Production; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1988 | BMW | 535is | 3.5L | L6 | N/A | Do Not Gap, Gap is Preset; Early Production; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1988 | BMW | 635CSi | 3.5L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1987 | BMW | 325e | 2.7L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1987 | BMW | 325es | 2.7L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1987 | BMW | 528e | 2.7L | L6 | N/A | Do Not Gap, Gap is Preset; To 12/1986; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1987 | BMW | 535i | 3.5L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1987 | BMW | 635CSi | 3.5L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1986 | BMW | 325e | 2.7L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1986 | BMW | 325es | 2.7L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1986 | BMW | 528e | 2.7L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1986 | BMW | 535i | 3.5L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1986 | BMW | 635CSi | 3.5L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1986 | BMW | 735i | 3.5L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1985 | BMW | 325e | 2.7L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1985 | BMW | 528e | 2.7L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1985 | BMW | 535i | 3.5L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1985 | BMW | 635CSi | 3.5L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1985 | BMW | 735i | 3.5L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1984 | BMW | 325e | 2.7L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1984 | BMW | 528e | 2.7L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1984 | BMW | 533i | 3.2L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1983 | BMW | 528e | 2.7L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1983 | BMW | 533i | 3.2L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
| 1982 | BMW | 528e | 2.7L | L6 | N/A | Do Not Gap, Gap is Preset; Available Until Inventory Is Depleted; Original Center Electrode Material is Silver; Silver |
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