Spark Plugs are Spark Plugs on a BMW, Right?? WRONG!
If you are inclined to change your own spark plugs on your BMW there are some things you need to know before heading out to the local auto parts store . . . just cause it’ll fit, doesn’t mean that it’s correct. There are many areas of the auto parts industry where quality and sound advice has taken a back seat to marketing and profit margins. One of these areas is the good old spark plug. I’m going to attempt to keep this simple and not too technical, which basically means you’ll have to trust me. (trust me, now that’s mechanic line if I’ve ever heard one.)
When you go to the auto parts store and order spark plugs for your 1985 535i they will have a neat little diplay that has about 5 different spark plugs ranging from what looks like a normal plug to one that looks like a space probe on the end. The guy behind the counter will tell you your options, all of them with code numbers that make no sense and he’ll eventually tell you how great the platinum ones are with the 4 prongs at the top.  STOP! You need to go in there knowing exactly what you need, and getting only that item. Most people will get the platinum spark plugs by the way.
