quattro digest, Vol 1 #4698 - 13 msgs

[Larry C Leung]

Hydraulic Journal bearings work on dynamic viscous pressure, caused
by the relative motion of the solid parts. Once everything is moving,
there IS no wear between the metal parts, unless there are suspended
particles in the oil. The only deteriment of the thicker oils are:

Slower pump up to the head in COLD temps (although this is GREATLY
alieviated with full synthetic oils)

More viscous friction, therefore, less horsepower and fuel economy,
but NO greater wear.

Bear in mind, MOST older German engines were designed for thicker
oils (which means LARGER bearing cap vs crank/rod clearances) to
reduce the chance of wear in autobahn conditions. As oils have improved,
the need for thick film lube has been reduced, however our older cars
actually
need the thicker oil to create enough pressure to fill the designed in
gap.
Follow the specifications given in your owner's manual or Bentley shop
manual.
There are specific reasons for those.

LL - NY


> From: "InfernoCL" <infernocl at wi.rr.com>
> To: "'Fred Munro'" <munrof at sympatico.ca>,
>         "'Al S'" <zeus83858 at icehouse.net>,
>         "'quattro-list'" <quattro at audifans.com>
> Subject: RE: what syn oil to use?
> Date: Sun, 9 Mar 2003 13:35:04 -0600
>
> 15w-50 is just a waste, them super heavy oils just rob power and
> decreases
> protection. Any synth oil today should offer enough protection for
> any
> engine including F1 engines. But its true old engines should stay
> away from
> 0 weight, 10w-30 works fine though.
>
> Remember thick oils robs power, increase oil pressure and have more
> engine
> wear......
>