[s-cars] oil consumption

[Paul Gailus]

I'm sure that there are a lot of factors affecting oil consumption,
but a higher viscosity will tend to leave thicker oil films behind on
the cylinder walls, therefore causing more consumption.
And zero oil consumption is not necessarily a good thing, because
it could imply that very little oil is getting to the first compression
ring.

I've also heard that oils with relatively low viscosity at room
temperature could make an engine more susceptible to corrosion
if it hasn't been started for a week or more. Not surprisingly, this
is because a thinner oil will eventually drain off and not stick to
parts like a thicker oil will. This has been observed with aircraft
piston engines, where some claim that the old straight grades are the
best for engines that aren't run everyday. So the 0W-xx grades may
not be the optimum choice for a car you don't run very often, especially
during the warmer season.

Paul


----- Original Message -----
From: <stefan13 at att.net>
To: <s-car-list at audifans.com>
Sent: Tuesday, February 08, 2005 11:16 AM
Subject: [s-cars] oil consumption


> During the recent timing belt install, my mechanic changed the oil and put
Pentosin 5w-40 in the car.   I previously used only Mobil1 10w-40 (green
cap), which the car consumed at a rate of about 1 qt per 3,500miles.  with
the 5w-40, the car uses absolutely no oil, nada, zilch.  Somehow, this seems
counterinuitive, and I am wondering if this is due to the viscosity or a
manufacturing difference.
>
> As always, thanks for any input.
>
> Stefan
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