Auto maint questions???

[Daniel Hussey <GY3WSX@VM.SC.EDU>]

     Hey y'all.  I am doing a speech for my speech class on basic (and preventa
tive) automotive maintenace, and although I've got this down pretty well, I sti
ll have a few questions, most of which will be obvious to the majority of you.
Some I think I know about, but not sure on.  Any help would be appreciated.

     1. Oil viscosity.  I know what this is for the most part, but I can't expl
ain it that well.  Any good definition of this?

     2. I think part of the reason synthetic motor oil protects so well is that
it creates a molecular bond to the metal engine parts (the Syntec commercial wh
ere they drain the oil out of the car and it is still running comes to mind).
Is this true?  It also has a higher viscosity, correct?

     3. 5W 50 motor oil.
        ^^
        I know this is the weight, but what is the "50"?  What does this stand
for?  I know the differences between a 5, 10, and 15 weight motor oil, but what
is the difference between the 30, 40 and 50?

     4. I know it is very important, especailly on Audis, to torque down the
lug nuts to the factory specs, but why?  Any brief explanation would be much ap
preciated.

     5. What is the interval for changing the fuel and air filters?

     6. How often should you normally check spark plugs (you can tell a lot by
looking at them)?  And, when do you normally change spark plugs?  Dist cap and
rotor?  And, what does the rotor do?

     7. How often should you flush coolant and add fresh coolant + water?

     Any info on any of these questions would be appreciated.  Thanks.

                                                               Later,
                                                               Dan