BMW Buyers Guide - Once You've Bought Your New BMW
Once you've bought your Ultimate Driving Machine you need to do two things. If it's a used car use Zymol HD-Cleanse or a similar cleaning agent to spruce up the paint work and secondly put some Redex / Techron into the fuel to give the injectors a good clean (most petrol stations sell it). Be sure to check all the tyre pressures and learn what their correct values are. Also check the spare wheel isn't flat, they almost always are.
It's also a good idea to make sure you know where the fuse box is, some cars have two by the way. Better to find them now than in the dark by the roadside. BMW fuse boxes have space for spare fuses to make sure you have a good range. I always carry spare bulbs for each type I may need, this is a legal requirement in places like Germany.
Get some silicone spray with a straw attachment and use it to lubricate the window runners. Put a drop of oil on the door hinges.
Read the Manual!
You'd be amazed at the number of people who don't know how to operate the gadgets and systems in the car. What do all those warning lights mean and what should you do if one comes on?
Classic example is the driver who took their foot off the brake when the ABS started pulsing and hit another car as a result. Nobody told them this was the normal feedback when ABS was in operation.
You should know how to remove the spare wheel and fit it, sounds trivial but on a Z3 getting the spare out is a real mission.
Read the service history. Have a good look and find out what items have recently been replaced / serviced and more importantly what hasn't or is overdue.
Why a Clean Engine is Important
A clean engine is a benefit for several reasons. For one thing it is far easier to spot oil leaks and trace their source if the entire engine isn't covered in gunk, Also a clean engine is less likely to develop electrical problems due to dirt getting into connectors.
Cleaning an engine isn't as bad a job as it sounds. I'd advise against using a high pressure water jet. I prefer to spray a warm engine with a degreasing solution and leave it for a few minutes. I then use a bucket of soapy water and a small jug to pour water over the engine using an old paint brush to help on stubborn areas. Beware of brushing dirt into the recesses around the spark plugs as it can fall into the cylinders if the plugs are removed. Try to avoid getting harsh chemicals on plastic parts like BMW logos and covers. Avoid getting water near electric connectors.
Things to replace
Nothing lasts forever, not even BMW components. I'd replace the following parts on any older BMW I bought unless the service history said they'd recently been done..
Spark plugs - be sure to get the correct ones
Air filter(s)
Cabin microfilter
Change all the fluids if you're in any doubt
Engine oil
Coolant (every two years)
Transmission fluid, especially on automatics
Final drive fluid
Power steering fluid if it looks dirty
Brake fluid (every two years)
Timing belt every 50,000 miles or 5 years (if fitted)
Hydraulic and alternator drive belts if worn.
Preventative maintenance on BMWs is always money well spent.
Check the Drains!
BMW doors have little drain holes at the bottom. Water will always mange to get inside the door skin as the join at the window is never perfect, the drains let the water out. If the drains block with silt the bottom of the door will rust out as happened to my mates '82 635CSi.
Some BMWs also have drain holes in the sills and the spare wheel well. If the ones in the spare wheel well get blocked any water leaking into the boot will gather until you get 6 inches sloshing around the spare wheel, ask me how I know....