Knowledge Base
Bought a Used BMW? Do These 12 Things First
Bought a Used BMW? Do These 12 Things First
Congratulations on your purchase. Now let's make sure it doesn't become a money pit. Here's your day-one checklist.
Immediate (Day 1)
1. Full Diagnostic Scan
Before anything else, scan every module for fault codes. Use ISTA, Carly, or BimmerCode. Write down every code — even stored/history codes tell a story.
2. Check All Fluids
- Engine oil — level and condition (dark = old, milky = coolant contamination)
- Coolant — level and color (should be blue/green, not brown)
- Brake fluid — should be clear/light yellow, not dark brown
- Transmission fluid (if accessible) — should be red/pink, not brown/burnt
- Power steering fluid (older models)
3. Inspect for Leaks
Park on clean cardboard overnight. Check for:
- Oil drips (brown/black)
- Coolant drips (green/blue, sweet smell)
- Transmission fluid (red)
- Power steering fluid (light brown)
First Week
4. Change the Oil
Regardless of what the seller said, change the oil and filter. You don't know what oil is in there or when it was actually changed.
5. Inspect the Cooling System
Look at the expansion tank for cracks or white residue. Squeeze the radiator hoses — they should be firm but flexible, not rock-hard or mushy.
6. Check the Brakes
Measure pad thickness and rotor thickness. Look for uneven wear. Test the brakes at various speeds.
7. Listen for Noises
Drive with the radio off and windows down:
- Cold start rattle? (VANOS, timing chain, wastegate)
- Whining at speed? (wheel bearing, differential)
- Clunking over bumps? (control arm bushings, end links)
- Grinding when braking? (worn pads)
First Month
8. Change Transmission Fluid
Especially if there's no record of it being done. Fresh fluid is cheap insurance.
9. Change Differential Fluid
Same logic. €30 in fluid can prevent a €2,000 differential rebuild.
10. Register the Battery
If the battery was replaced without registration, the charging system is misconfigured. Register it with ISTA, Carly, or BimmerCode.
11. Check Recall Status
Enter your VIN on BMW's recall checker. Complete any outstanding recalls — they're free.
12. Join a BMW Forum
Seriously. The collective knowledge of the BMW community is invaluable. Model-specific forums will tell you exactly what to watch for on your car.
Total cost of this checklist: €200-500 in fluids and filters. That's nothing compared to the cost of the problems you'll prevent.