From: jimv@hienergy.Eng.Sun.COM (Jim Vienneau  - Sun Microsystems)
Newsgroups: rec.autos.tech
Subject: Re: Dirty oil after change?
Date: 10 Sep 1992 20:52:26 GMT
Organization: Sun Microsystems, Billerica, MA.
NNTP-Posting-Host: hienergy.east.sun.com
Keywords: oil changes

In article <1992Sep10.171455.28660@swlvx2.msd.ray.com> hsd@swlrat.msd.ray.com (HERBERT DASILVA) writes:
>hugo@bluehau.bubble.org (Hugo Bueno) writes:
>>I've done countless oil changes on cars and I have YET to see
>>one that has clear oil after the change.  This even includes
>>changing the filter and using engine flushes.
>
>>Hugo Bueno
>
>  Honestly, it sounds to me like you're not changing your oil often enough.
> Much deleted...

You're both missing the mark here. Clean oil is not good oil. It's the
oils job to suspend particles. If your oil gets dirty sooner, it's only
becasue it's doing a better job or there is more material to suspend.
Some engines are just looser than others and have more blow-by. Also,
seasonal changes make a difference. Up here in the cold north, the choke
stays closed longer in the winter months. The rich mixtures cause more
soot which also darkens the oil. In January, my freshly changed oil
turns dark in less than 1K miles.

The only way to tell if your oil is still doing it's job is to have it
chemically analyzed. I used to do this from time to time, but don't
bother now. My opinion (everyone has one!) on oil is:

1) All namebrand "SG" rated oils are pretty much the same, buy for price.

2) All namebrand oil filters are suitable for the 3 to 5k change interval.

3) Synthetics are better than petro based, but are not necessary for the
   average driver (racing, towing, or other high load duties is a
   different story).

4) Change the oil and filter every 3 to 5k and you will not have any
   oil induced failures.

Everyone also has these stories: I've driven every car I've ever owned
well over 100K with no problems. The last was a Buick V6 that had 172K on it
and was still going strong. 

The truth is: LACK OF MAINTENANCE is what kills most engines, not what brand
of oil you use or if it's changed at 2K or 5K. Most people just don't
seem to change it at all or at 20 or 30k when they think of it. This is
doubly true for automatic transmission fluid.

The other truth is: trust no one to work on your car. Dealers and garages
are there to make a buck off you, they don't care if you get 50K or 250K 
out of your car. The quick lube places WILL NOT grease your car (they
know you can't tell) and may or may not damage the drain plug, replace the
filter, etc. The dealers and garages will misdiagnose your problem and replace
good parts. When they find this didn't fix the problem, they will claim
that the already replaced parts were bad too. The auto repair and 
maintenance industry is as crooked as they get (OK, there's probably a
few honest ones, but I haven't found one yet).

Sorry, I kind of got off the track a bit (a bit jaded I guess, or maybe it's
experienced). The bottom line is: Do reasonable maintenance, make sure it's 
done right (ie, do it yourself), and you'll be sitting pretty. Don't worry 
about the oil getting dark, it's just doing it's job.


--
Jim Vienneau, Sun Microsystems Inc - Billerica, MA
Email: jvienneau@east.sun.com   Amateur Radio: WB1B
Good old Ma Bell (well old anyway): (508)671-0372