Here's a general outline of the process, but I strongly recommend seeking professional help:
1. Locate the fill and drain plugs: These are usually on the bottom of the gearbox. You'll need a workshop manual specific to your year and model of Focus ST170 to pinpoint their exact location and the correct size of Allen key or socket required.
2. Warm up the gearbox: Run the car for 10-15 minutes to warm the oil. This will make it flow more easily.
3. Drain the old oil: Position a suitable container under the drain plug and carefully remove the plug. Let the oil drain completely. This can take a while. Note the amount drained – you'll aim to replace roughly this amount.
4. Refill the gearbox: Once drained, locate the fill plug and carefully remove it. Using a funnel and the correct type of gearbox oil (consult your owner's manual or a Ford specialist for the correct specification), slowly add new oil. You may need to use a pump to get the oil into the gearbox.
5. Check the oil level: This is the tricky part without a dipstick. The method varies slightly depending on the gearbox type (MTX-75 is common in ST170s). Some methods involve refilling until the oil starts to flow out of the fill hole, others involve measuring the amount drained and replacing the equivalent. Your workshop manual is crucial here.
6. Replace the plugs: Tighten the drain and fill plugs securely to the manufacturer's specified torque. Using a torque wrench is highly recommended to prevent damage.
7. Test drive: After refilling, take a short test drive to ensure the gearbox operates correctly.
Crucial Considerations:
* Gearbox Oil Type: Using the incorrect oil will severely damage your gearbox. Consult your owner's manual or a Ford specialist. The viscosity and specification are critical.
* Workshop Manual: A workshop manual specific to your year and model Focus ST170 is essential. It will show you the exact location of the plugs, the correct torque settings, and the proper procedure.
* Safety: Working under a car is dangerous. Always use jack stands and follow proper safety procedures.
Because of the complexities and potential for damage, it's strongly advised to take your car to a qualified mechanic for a gearbox oil change. The cost of repair from incorrectly refilling will far outweigh the cost of professional service.
