Can we compile a list of average life in years or kilometers for mechanical parts on the 3rd gen especially in the case of preventative maintenance?

I've heard a good time to change water pumps on cars is around the 160,000km mark but this would likely be better done with a timing belt I assume?
O2 sensors seem to often fail around 160,000km from what I've read on these forums, and the rocker cover gaskets leak around there too.

How long do spark plug leads generally last?
And any other parts that need replacing every so often?

For a lot if not most parts you are not able to do this as there are so many factors involved such as how the car is driven ie city or country mileage, how hard is the car driven, gas or no gas etc etc. There are so many factors involved with these things as well as the quality of the parts fitted it is near impossible to state anything about how long parts last

Things like timing belt and water pump sure, rest of the car not possible

Platinum plugs generally last 100k. Had nil problems with any i have used and have gone the distance without difficulty.
Does not mean other people have had the same amount of luck though.
Had the odd waterpump not make 100k so as Madmagna says most are unkown quantity. You will finds cars that do not get driven much and sit for long periods have greater low mileage part failures. Vee

You are better off keeping a list in your mind about what things are prone to fail, and check those when you have problems, rather than replacing them as items you would swap out at a certain km.
Having said that, have you checked drive shaft and steering rack boots lately? lol

Yes I checked not long ago and they are fine.

I am just wondering whether to change the leads primarily as they are the original ones at 181K km today

Yes I checked not long ago and they are fine.

I am just wondering whether to change the leads primarily as they are the original ones at 181K km today

Unless you like to fiddle with things, I'd leave them alone until (if ever) they give you trouble.

I planned on changing spark plugs and thought maybe do it all at once if they would make the car run better at all

If you have the intake off to change the plugs then change the leads.... Makes a lot of sense rather than pulling the mani off twice.

If you have the intake off to change the plugs then change the leads.... Makes a lot of sense rather than pulling the mani off twice.

As long as the new leads are of good quality and you don't end up introducing problems where there were none to start with. Some people have had problems with after market leads. And have a really good look at how the original leads run, and duplicate that exactly. No slack at all in most of the original leads, so check each new lead against the original for length. A cm or more short can give problems.

For starters why change leads if there is nothing wrong with the old ones. Secondly anyone using any aftermarket lead to save $10 bucks is a fool, the amount of aftermarket leads I change in my shop because they keep popping out of the holes, fall apart etc etc is astonishing. Lets face it, the genuine leads are on many Magna's still the original leads so are over 10 years old on the average car, why not replace with another set of quality leads which will generally last another 10 years.

some parts (e.g coolant, timing belts) have life spans however it is mostly on a case by case basis.for example at work have cars that are 5 years+ and ones that are under/over 250,000 that run like a dream yet have cars that cant drive 5km from the dealership without needing a tow back(believe it or not this has happened)