Re: Mobil 1(and vac. leak)

[David Weiss <dzweiss@worldnet.att.net>]

On Mon, 24 Feb 1997 11:25:52 -0600, Raj AUDIocee wrote:

>Now I have a 84 4000s(5 cyl) For the most part
>I used PENZOIL with a fram filter, after a while the lifters became
>noisy. I changed to use CASTROL GTX with a FRAM dual guard filter (with
>teflon additive) This combo did wonders for my car, no more lifter
>noise. The next oil change was with MOBIL 1 and a Bosch filter. The
>lifter noise is back, but I have smoother revs at 4500 rpm. Next time I
>am going with CASTROL SYNTEC.

I've stayed out of the synthetic thread(s), but feel the need to add
$0.02.  As a chemical engineer who manufactured lubricant additives for
a number of years, I have first-hand experience with an issue which
hasn't been addressed here:  additive compatibility.  Basically,
additives can interact chemically with each other, causing precipitation
(solids, not rain).  We were very interested in this, and had some
screening tests for various additives.  One test was blending up a
mini-package, holding at ~100C for a couple of days, and then checking
BS&W (Bottom Solids and Water, or Bottom Sediment and Water).  We
checked our additives and those of other manufacturers.  Several % BS&W
was not uncommon.  You don't want to know the worst ones.

When the translucent plastic containers first came out, it was easier to
see trace sediment before it went into the engine.  We observed some. 
The industry seems to be more sensitive to this now.  With a single
brand/type of oil, the risk of interaction is low.  There is no
guarantee you won't have an interaction problem when mixing brands. 
Shell is the only motor oil manufacturer I know of that publicly
acknowledges doing compatibility testing, perhaps because they had a
poor reputation in the past.  They say they haven't seen any interaction
problems between their oils and other brands.

The best course is to pick a quality oil that is available wherever you
will be driving, and stay with it.  Switching brands every oil change is
just upping the odds you'll have a problem.  As for the snake-oil, you'd
think those folks would do a lot of compatibility testing...

For the record, I use Mobil 1.  I would like to see some fleet wear test
results, though.

--Dave Weiss
    '91 V8 5-spd
    '93 90 CS UnQ