OK, in no particular order:
RE: Washers, et. al. - having SEEN and/or been a part of having several brake sealing washers "leak" (i.e. fail at their job) when re-used, I've deemed it "necessary" to replace them when I do a job on a street bike. Race bikes are a different story - you assume the risk and you choose to save the money/parts. As for not having them on hand, if you could manage to plan to buy brake lines and brake fluid, how can you not manage to add in the brake line washers. It is a matter of "insurance". If you're comfortable reusing a cheap part on brake systems, go right ahead. My sole point is that when you're considering street riding, if you need brakes and don't have them, was it wise to save the $0.50 on the brake system rebuild? Yes,
normally the worst that happens is weeping brake fluid from the fitting - will you notice in time to keep the brake fluid from "eating" the finish / discoloring your rims, forks, and perhaps fairing parts near the fitting?
RE: Oil Drain Washers - I won't speak for other brands, but for BMWs, you're flirting with at least a decent oil leak if not outright drain plug loss. I've delivered the "you're fucked" message to more than one customer who reused his drain plug washers doing his own oil changes and had lost the drain plug while riding. Again, I don't know of a single person who buys oil filters without oil to do an oil change. How hard is it to also buy a washer at the same time? The factory BMW oil filter kits come with the drain plug washers. And why not just keep a set (2-3) on hand in your toolbox anyways? If a new crush washer keeps your bike from leaking (or in the "rare" case, drain plug/oil loss), how much have you saved that you'll loose in time cleaning up the leak, bike, and lost oil? I'd bet that its a lot more than the cost of the sealing washer.
RE: Using a torque wrench for tightening critical items - YES! (although, in the interest of complete disclosure, and at the risk of being branded a heretic / hypocrite, I don't use them on oil filters and drain and fill plug washers, as I have enough experience to know the correct "feel" of them tightening down to the correct sealing torque. I do use them on brake line fittings, even to the point that I have crow-foot 'sockets' for use on line fittings).
RE: Mechanical Advice - In the absence of knowing the person's experience level (i.e. are they qualified by training and/or experience) to know if its OK to reuse a specific part, I'll tell them to error on the side of DON'T, as it gives the new / fledgling mechanic the job success he/she will need to keep on the path of wrenching themselves. An early job failure - especially one that results in damage to the bike - can drive a person away from every doing such operations themselves. Quite honestly, we all spend quite a bit of "discretionary" income on our hobby/passion - motorcycling. Can any of us truly say that we couldn't scrounge the cash to buy sealing rings/washers for these operations when needed?
Sometimes, I forget that people can't realize that some of my posting(s) are
P.S. And no I don't park my bike at the exact spot it has when I cross the mileage "limit" - I usually go to the nearest parking lot and call a tow truck.
