The dealer probably uses whatever they get cheapest (bulk) that meets
SAE; and API standard SM, though SL is still around.

Hi,

Your owners' manual will spec a weight and service grade, e.g 5W-30 and
API grade SM. Close your eyes and pick one... the biggest differences
between brands is price, and the biggest difference between dino and
sythetics is more price. The rest of the "differences" are generally
arguable at best. Nobody's selling "bad" oil under a known brand...

As for the dealers' choice? It's my understanding my local dealers all
have deals w/ oil distributors, and the "cheapest is what we use" idea
seems to hold. My Subie dealer likes Castrol. My Toyota dealer uses
Pennzoil in the shop, but will sell you "Toyota" badged oil if you walk
into the parts dept. I've seen a Valvoline sign at another dealer. It
goes on...

Rick

On 17 Dec, 10:46, fly1...@aol.com wrote:

I'm doing the motor oil mambo. Started questionioning the GL-5 gear
oil in the manual trans, since it wasn't shifting as easily as i
thought it should, and found out the recomended oil can corrode yellow
metals, which the syncronizers are usually made of, and that happens
because of sulfur added to the oil, that can form acids at high temps
that some can the oil doesn't reach, and others say it can. I guess
that's why they recomend changing it, I believe at 30K mi.

 I wanted to use synthetic motor oil, and that is getting crazy. Read
that Mobil one isn't pure synthetic, because of the mineral oil
additive package, that makes up 20% of the oil,  and highly refined
Group III mineral oils can be called Synthetic, and what most co's
switched to that they call synthetic. Synthetic oil isn't recomended
for breaking in, because it is too slippery, and doesn't allow the
friction, to wear in the metals, Though some cars like Corvetts come
with it from the factory, So who is right?

 If you are just interested in mineral oil, I'd say any name brands
should be good. Years ago I  had a car starting to burn oil, and
switching brands stopped it. They Used to say, that Penna. oils were
better because they had a waxy, paraffin base, but Now they say that
Isn't good, and what forms sludge.

 I've read that oils Actually lubricate better the older they are, to
a point,  but the additives wear out, and changing the filter and
toping it off with freash, extends the oil a lot, and the Most wear is
in the first 3K mi. This may have been with synthetics, since that's
the most info I've found available.

 I have an 07' Impreza that I recently got, and want to use synthetic
in it, and stay with the maintance schedule, and a 20yr old Chevy,
that uses a qt between changes,  that I plan to use the synthetic I
drain from the Sube, put a new filter, and top it off with fresh oil.
I don't drive that much now, about 4K mi/yr, though plan to be doing
more, mainly in the Sube, and highway miles, so the oil still should
be good for the Chevy.

 I have the post about the dealer pestering me to have the oil
changed in the Sube at 3.5K mi. The letter even calculated that I
Probably have 3048 mi on it 2 weeks ago, when the car was 3 mo old. I
live in a big city, which may be why the dealer Thinks I should change
it now, but I only have 1700mi on it, in the 3+ mo, and mostly  drive
the Sube in it to get to the highways, and the stop & go around town,
that Would be a reason for recomending more frequent changes, isn't
starting it up, driving a few miles, and shutting it off.

VF

After recently looking at the condition of wear surfaces in the engine
of my 94 Maxima (virtually no wear, original grinding marks perfectly
visible), and finding no oil sludge when replacing the rocker cover
gaskets, I was glad to have used Mobil 1 since the first change.