burning oil?

[treed2@u.washington.edu (T. Reed)]

Okay, this is a common debate - whether or not a low temp thermo will
affect your "final" engine temperature or just cause your engine to take
longer to warm up.

My answer is of course that it will.. thermostats are generally
bimetallic strips containing two metals with different coefficients of
expansion. In this design, the thermostat "valve" action is continuously
variable, not a discrete on/off behavior. So unless the engine temperature
is significantly above the temperatures of both thermostats, a low temp
and a normal temp thermostat will behave differently (ie. be open
different amounts at the same temperature). Different behavior causes a
different result. Namely, that the low temp thermo runs colder.

By the way I do have a low temp fan switch and the thermo they gave me was
the lowest I've found - 71 C compared to stock (87 C).. that's almost a
30 F difference. Trust me my car runs icy cold all the time, unless like I
said I drive it hard then idle it for 20 minutes. Even after it warms up
that way if I start to drive it again the temp will quickly drop to icy
cold again.

Initially I didn't mind the lower temps but now with my engine burning oil
and my heater barely functioning I bit the bullet and bought a new water
pump and thermostat.

Before I put the 2.0 in I had a standard thermo and I replaced it as a
precaution - the parts place gave me the low temp one on accident but I
decided to try it anyway. With the 1.8 my temp shot up to the LED and
stayed there after about 3 minutes. It occasionally rose above the LED
during the summer in traffic.. but generally stayed right at the LED.

I've also read in the past that the 16v motors were designed to run hot.

Anyway, I just wanted comments on my theory. I did a little web "research"
on the topic and several sources I found (who knows how credible they are,
but..) say that putting in too cold of a thermostat will cause increased
fuel and oil consumption and engine wear. Reasons cited included
expansion/contraction of rings and valve seals..

The only good thing that has come out of this is I finally got off my
keister and installed seat heaters in my seats. More info on that soon..

-Toby

On Mon, 24 Feb 2003, Michael Abatzis wrote:

> don't see why the low temp thermo would do that. once the thermo's open,
> it's open; the water just goes to the radiator earlier. the engine should
> still get up to normal temperature. only way i see that that would have an
> effect is if you also had a low temp fan switch AND you were doing a lot of
> city driving.
>
>
> -Michael Abatzis
> Hotlanta! GA
> 1988 Scirocco 2L 16v RIP-->parting, finally taking orders:
> www.learnlink.emory.edu/~mabatzi/mikes_page1.html
> 1987 Scirocco 2L 16v...
>
>
> >From: "T. Reed" <treed2@u.washington.edu>
>
> >
> >That was my theory until today when it occurred to me that when I did the
> >engine swap they gave me a 71 C (super low temp) thermostat instead of the
> >standard thermo I asked for. I've been driving the car with it out of
> >laziness (don't want to bother draining the coolant just to change it) but
> >the side effect is that the car never warms up. It always stays very very
> >cold, in fact my heat barely works at full blast after 1/2 hour of
> >driving. The only time the car warms up is if its been taken for a hard
> >drive and then I stop and idle it for 20 minutes. Then it will come up to
> >what I consider "normal" operating temperature - the water temp needle at
> >the LED on the gauge.
> >
> >after that, I guess. But in the mean time.. should I be reading up on
> >valve seals and what kind of a job that is or do you think my theory has
> >any validity?
> >
> >-Toby
> >
>