Re: Auto maint questions???

[Alexei M Voloshin <Alexei.M.Voloshin-1@tc.umn.edu>]

>      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?

Viscousity is a measure of shear stress distribution in liquids. For 
newtonian liquids, the relationship of viscousity to shear stress is 
linear. For non-newtonian liquids, it is non-linear. Oil is a newtonian 
liquid. 

> 
>      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.

It has a viscousity of straight 5 grade oil at 0 degrees C and viscousity 
of 50 grade oil at 200 C. That is why such oils are called multi-grade oils.


>      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.

So you don't warp parts and make sure parts are screwed secure to each 
other.

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

30k miles


> 
>      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?
> 
Ususally every 30k miles.

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

Also 30k miles or 24 months.
>


Alex