95 525i Spark Plug choices

[genphreak]

Seems as if the NGKs get more votes all right - thanks for that. And yeah the aftermarket cat might not last as long as I would like - yet it buys me some time (I hope) to fix other stuff - drivers window, a/c, radio. Already did suspension, head gasket, transmission (I had blown 2nd gear). Typical big-project (for me) stuff.

One option is to buy a cat from a later model that will fit, you will need to check inlet and outlet sizes and have a good shop tig it up of course. I gave up using Bosch plugs ages ago, the NGKs are fine, nothing wrong with choosing them. Make sure she doesn't have a small air leak- both the connection to the brake booster (it has a small plastic nipple right on the right angle inlet to the booster that is very brittle. It breaks when you look at it, if it isn't snapped off already. Normally it is blanked off w a rubber bung, but if broken there will be a 1.5mm hole visible on the plastic connector, where it once was). Also, other places the vacuum can be leaking- oil cap seal and the multi connector going into the back of the plastic inlet manifold, directly behind the throttle plate where you can't get to it. You have to remove the alternator and all sorts to reach it. It has an o-ring, and is held in by a plastic clip that sticks out and breaks. Cheap to buy new with the ring, just grease the ring first as sometimes they are hard to seat- I've seen lots that haven't been fitted properly.

Oh and the valve cover gasket, it can leak air, and the two seals around the plugs that poke through the valve cover. If you find oil in the plugs, it's a telltale sign that the these VC gaskets are bad- all of them. You'll probably need to replace the rubber nut seals too- they can be bought together as one lot easily enough.