the issue I have with torque wrenches? It's a big ass breaker bar. You have no idea of the stress you're putting on things when you use it. Oh sure, you have a number you are pretty sure this bolt needs. But what happens when you apply foot-pounds and the spec calls for inch-pounds? Or you read 125 ft-lbs. but that is for another fastener and the one you are on needs 65 ft-lbs? You are two feet removed at least from feeling the stress on the part, so breaking bolts is easy. You'd know to stop if you relied on feel, but since the torque wrench hasn't clicked, you keep leaning on it until it snaps.
And at the end of the day, you don't know how tight it is, you only know your torque wrench clicked or slipped. You were at the end of a breaker bar, so your concept of how tight it is might as well come from Mars. I'd rather have a tactile feeling of how much pressure I put on things. At least then I know it is tight or loose or whatever. I am not a monkey, so I can tighten things just past snug, or lean on it, or just bring it to the seat. On the end of a breaker bar, I won't know if it is seated until the bolt snaps.
Would you feel better if your engine ejected a plug but you "torqued it to spec"? Or would tightening it by hand so it is snug using a regular ratchet give you peace of mind? I know where I stand. I'm not going to rely on a torque wrench to tell me my lug nuts are tight. You mileage may vary. If my wheel falls off, I'm not going to make it better by saying "but I used a torque wrench!?!"
Torque numbers are just numbers. Kind of like tightening sequence. If you can't look at a part and guess the sequence, you *need* the instructions. But it should be obvious. Engineers aren't geniuses, they just study and break parts and try again. Sometimes they only write instructions after someone breaks parts. The average person can grasp what is required with a bit of thought and a modicum of experience. Tightening sequences and torque specs are written for the idiot quotient. An idiot is someone who can't figure out how to tighten a wheel, or reads the instructions on how to tighten a wheel and doesn't figure out that a head should probably be tightened the same way.
Most people aren't idiots. Just don't tighten everything to German "gooden'tight" specs irrespective of the part. That's just stupid. Plugs only need to be snug. Wheel lugs need to be tight, but only arm tight, not body-weight tight. And not gorilla-arm tight. Check and re-tighten lugs after driving a mile or so. Check plugs the next time you change your oil just to be smart, but use your fingers. If your fingers can move them, get out the wrench, but not before. And grab it around the socket, not at the end. You DO NOT want to break a plug off in your head, or strip the head.
Seriously, you should be able to interpret torque specs into "arm calibration." I understand if you work at shop why you rely on the tool. But even in shops there are gorillas who break bolts, strip drain plugs, and generally make a mess even with torque wrenches. They're the guys telling you that you have stripped wheel studs or need to replace head bolts after an oil change. Obviously torque wrenches don't solve the world's problems :/
All that said, perhaps I'm not typical. I'm not the kind of person to say I have skills you can't learn. But what do I know? Some people have perfect pitch. Is it possible for a person to have perfect torque?
(I'm not saying I do. I'm just saying perhaps I'm naive and know things I don't even know I know)
And for the record, Honda's S2000 is known to eject the #4 plug. Same issue, but Honda blames the customer rather than re-spec the part or fix the problem. Think of that before you blast Ford. At least they suggest a different plug.
I'm not disputing the posts before me. They provide good info, and are coming from intelligent people with real world experience. I'm just saying that torque wrenches are not a panacea. They provide "scientific" torque used correctly. But the kicker is the "used correctly" thing. Often you are better off not using one than risking using one incorrectly in your driveway. And truth be told, even "torque to yield" head bolts can be tightened properly without one.