I thought it would be nice, since we have so many wonderful mechanical guys/gals, and so many burning questions, to sap their brains for repair opinions (assuming they are willing to be sapped, that is :D).
I’ll start:
What circle of Hell would I be entering if I try to install new spark plugs in my '02 (E39) BMW 530i? I’ve watched tons of YouTube vids and read some tech stuff, but fear remains in my soul. I bought NGK replacement plugs and possess a crapload of metric wrenches.
plugs on your car should be a piece of cake. it’s coil-on-plug (one ignition coil per spark plug) so no plug wires to deal with. all you have to really worry about is not over-tightening the new plugs. oh, and use a proper spark plug socket so you don’t crack the ceramic insulator.
. . . so I’m deriving some courage from this 
Yeah, I’ve given up almost all car repairs but I’d still change plugs as long as I can reach them and see them from the top. And change the wires too while you’re at it. One wire at a time, don’t disconnect more than one of them at a time no matter how sure you are you know which is which.
one of my favorites were the NS/RS Chrysler minivans (1996-2007.) by far the easiest way to change the rear bank of spark plugs was to raise the van on a hoist and get at them from below.
PROTIP: you definitely want to make sure it’s fully cooled down, because you’re going to be hugging the catalytic converter during the job.
Four I’ve encountered:
2003 Nissan Sentra. Really really simple, the coils and plugs are right there in a row at the front of the engine compartment when you open the hood. No plastic engine covers either. Took like 20 minutes.
2008 Mazdaspeed 3. A bit more complicated because the turbo intercooler had to be removed. But other than that, about an hour’s worth of work IIRC.
2008 Nissan Versa. I thought this would be easy but between engine covers, needing a deep skinny 14mm socket that I didn’t have at the time, and needing to mess with coolant I let a shop do it.
1995 F-150 w/302 V8: Old traditional distributor with fat plug wires going to the plugs. Relatively easy except there are 8 of them and the passenger-side plug is pointed towards the firewall. You need a swivel extension to get to it, or just remove the wheel well cover.
Spark plugs can range everywhere from doing it blindfolded to being a truly Sisyphean task. But if it looks doable from the YouTube video, go for it. As jz78817 pointed out, using a spark plug socket is highly recommended to avoid cracking the new ceramics. There’s usually a foam insert in the socket to protect the plug.
Ages ago, I needed new plugs and wires in my Aerostar. It didn’t take long for me to decide that it needed to go to a shop. Because sometimes the best tool for a job is a checkbook! In fact, except for wiper blades and windshield washer fluid, I take the car to my car guys. Stuff that was fun when I was in my 20s has lost the charm now that I’m in my 60s.
One of the most idiotic things I ever encountered was when the headlight on my daughter’s New Beetle burned out. The manual said to take it to the dealer… for a HEADLIGHT!!! But thanks to my mad Google-fu skillz, I found step-by-step instructions with photos. It wasn’t an easy task, but it was doable, and my daughter did it. In fact, she had to do it several times over the life of the car, and those instructions lived in the glove box for future reference.
Wasn’t it the old 4th generation of F-bodies (Camaro, Firebird) that required you to loosen the motor mounts and hoist the engine to get at one of the rear plugs? I seem to remember a lot of guys would change 7 and just hope the final cylinder was OK.
It seems pretty straightforward, it’s a straight-six and I (experimentally) removed the engine cover to make sure I could actually see what the video showed. I plan to do one at a time, taking pictures at each step for when I forget/drop/get pissed off when I can’t put something back together.
My uncle had a Beetle in the 1970s that was a '66 (or close to it). I went on a lot of trips with his family and the car would breakdown approximately every 200 miles – but it was easy to fix; uncle would pull out a bobby pin or piece of barbwire and get it rolling again.
The headlight thing isn’t weird in the light of BMWs (at least my older one). The freakin’ lens covers are basically welded to the frame, therefore requiring a mechanic if one doesn’t want to go to it with a hammer :mad:
The only “in the way” component I can see is the cabin air filter, which is easily removed (at least according to the video).
I just ordered a spark plug socket wrench and new metric wrenches (I have a bunch, but they’re scattered all over my indoor and outdoor domains).
So here’s a stupid and potentially embarrassing question: the directions say to not exceed a torque of 30 when screwing in new plugs; if I’m doing this by hand wrench, how the heck do I know what a 30 torque is? 
if the directions use metric units, it’s probably 30 N*m. if they’re a conical seat (no washer,) if you don’t have a torque wrench then an approximation is to screw them in until the plug contacts the seat, then tighten 1/16th of a turn.
Useless spark plug trivia coming…
I used to have a Nissan P/U that had 8 spark plugs in a 4 cylinder engine.
I started my 1970 Volvo 144 one morning and heard a loud bang against the hood from the engine compartment. When I opened the hood, one of the recently changed spark plugs was just sitting on top of the engine still attached to the wire. Screwed it back in and worked fine.
(To change the spark plugs on a Pentastar JK, you have to remove the intake manifold. It was a pain in the ass.)
If you’re gonna do any serious work on your vehicle (as it seems like you already do), get a torque wrench - seriously. They’re quite cheap, and there’s nothing like knowing things are fastened properly.
I had forgotten about that, but I had one of those too. Exhaust side plugs to clean up the emissions a bit.
that’s not how it works. both plugs fire at the same time; the reason for dual plugs is to increase ignition reliability in a combustion chamber design with poor turbulence/quench characteristics. Those Nissan/Datsun engines had hemispherical combustion chambers (pic) which have zero squish/quench area and the lack of turbulence means they’re much more prone to misfires (spark fails to ignite the mixture) and detonation. dual spark plugs decreases the chance of those occurring. 's why the current “Hemi” engines from FCA still have dual spark plugs.
firing an “exhaust side” spark plug after the main combustion event would be useless; even if there were significant unburned hydrocarbons left over the overall mix would still be far too lean to ignite via spark.
Ok, but couldn’t dual plugs result in more complete combustion with some emissions improvement?
Speaking of BMW repair-
Does anybody have a Bentley Repair Manual that covers the e30 X-Drive that they would be willing to lend me?
