If you want to read a site which has a lot of info about auto oils, here is
an interesting one:

    http://www1.geocities.com/MotorCity/2195/engineoil_bible.html

36 responses total.

My neighbor, who just had her oil changed ('professionally') 8000 miles ago,
found her oil light blinking, and when she measured the level there was none
on the stick.  So she added a quart - still no reading.  There is no sign of
any leaking or burning of oil, the car is pretty new (a few years old) but
has 94,000 miles on it.  (Works in Dearborn).  Is it possible that the
'professional' only added one quart after draining the oil?  Or forgot to add
any oil at all?  Other ideas?
I doubt the website covers this one.  Help please!

She poured in another quart, still no reading.  The third quart gave a low
reading.  Does an oil fill evaporate in 8000 miles?

On most cars, the oil is supposed to be changed every 3000 miles.  If she went
8000, I'm not surprised there was a problem.

BTW, I'm assuming that if the oil had been that low when it was changed, the
oil light would have come on right away, rather than waiting 8000 miles.

   indeed. if the mechanic had added no oil, the oil light would have
come on immediately and the engine would have seized up within a block
or two of driving away from the oil-change place. with an aging car
that has that many miles on it, it's not at all surprising that a lot
of the oil had been used up/burned away. ideally, oil should be changed
every 3,000 miles and the dipstick checked at least once a month.

I will tell her all this.  Thanks.

My Nova, with about 120K on it, uses about 1 quart every 2,000 miles.
I change the oil on it every 3 to 4 thousand miles.  Seems like pretty
normal consumption for a car with 94K on it.  When the oil light comes
on it means that the oil pressure is low or not.  No oil pressure means
that hot moving parts inside the engine are not being lubricated which
can seriously harm or totally destroy an engine in short order.

My roommate (who keeps the car running, with 150,000 miles, by just pouring
in used motor oil once in a while, since at 1000 miles/year the body will wear
out before the engine anyway) said that oil filters should be changed more
often than oil to keep the oil cleaner, but that the filters most often sold
have pores too large to do much because the manufacturers know that people
wont change them, and this way they don't clog as quickly.  Any comments?
Where does one buy a better filter, and wht are they called?

   most manufacturers recommend changing the filter every 6000 miles
(ideally, every other oil change). i don't know of any "better" oil
filter, but you might want to call a reputable parts store and ask.
using dirty oil, even in an old car, doesn't seem like a very good
idea. the dirty oil will do a far less efficient job of lubricating
the engine and cause the engine to wear out much more quickly.

I have read that oil filters have high pressure bypass valves in them
to bypass oil during high speed driving and clogged conditions.
 
Oil has addatives in it that "wear out" with use.  I have noticed that
my mileage drops as the oil ages.

To quote from the audience (who pours in used oil), '
Baloney.  There is no way the mileage could be reduced enough to measure it.
And we don't care about the engine wearing out because, if you drive a maximum
of 1000 miles/year, the body is sure to wear out first.
I the old days, you were supposed to change the filter twice as often a the
oil.  And yes, he has heard about the bypass, and says only a portion of the
oil goes through the filter anyway, and if the filter is getting clogged, even
less oil will go through it.  But the average car owner does not follow
recommendations.  (Same as with taking antibiotics, they never expect anyone
to follow the instructions, so they give them more than they need.)  So cars
have been designed to run with dirty filters, less efficiently.  Nobody ever
used to change their filter between oil changes, so they redesigned the
filters not to catch as much dirt, and therefore the oil gets dirty faster
so you have to change the oil more often instead of the filter.

I suppose another factor might be that if you're using used oil, you would
need to change the filter more often.

Hmm... if I had to put in a new oil filter every 1500 miles, I'd probably be
buying them in bulk.  As it is, having to get an oil change almost once a
month is annoying enough.

The 3,000 mile rule is not what most owners manuals recommend.  Our Subaru
manual says every 7,500 miles and the dealer says changing it more often
is a waste of money and oil.  The general rule of thumb you see bantered
about is every 3,000 miles.  I suspect it has a lot to do with the size
of the engine in relation to the amount of oil in the sump.  I suspect that
and engine with a smaller oil sump would require more frequent changes,
all other things being equal.  A worn engine will have more blow-by and
gasoline / diesel getting into the oil will alter its characteristics.
An engine that is seldom allowed to run at operating temperature will
also build up more fuel residue and water in the oil since a lot of that
would be boiled off at operating temperature.  Operating conditions
(load, engine operating temp. etc.) also effect the oil.
 
I have whitnessed a ~10% drop in in mileage to, what I consider, old oil.
(Changed after 7,000+ miles in our Nova.)  A mechanic friend said he has
seen the same thing.

Saturn recommends changing the oil every 3,000 miles.  Since I'm doing a large
amount of driving ~500 miles per week, and I want the car to last a long time,
I'm being pretty careful about that.  Perhaps I'm wasting some money on that,
but I'd rather waste the cost of a few extra oil changes than the cost of a
new car.

One more thing:
        I've got a 15 year old Nissan pick-up truck, which I've probably driven
about 100 miles since I bought the Saturn in April.  I had the oil changed
a couple weeks before I bought the Saturn, but since then I haven't been using
it enough to justify the time to get stuff done to it.  The oil still looks
pretty much like new oil does, and there is still enough of it.  How important
is the "every three months" part of the 3 months or 3,000 miles rule in
vehicles that are almost never driven?

The other fluids all look like they're at the right levels except for the
coolant, which is low.  I have a bottle of coolant, and will add some coolant
before the next time I drive it.

I would go by what the manual says when it comes to oil changes.  I agree
that every 3 months for a vehicle that is hardly driven is pretty absurd.
When I used to be in that boat, I would change it every 3,000 miles or
every 9 months or so.

There used to be kits to test the oil to see if it needed changing.
It is the number of times you start the car that affects the oil.  The warmup
period, before the parts expand and fit as designed, is when there is the most
engine wear.  You can change your oil every week, but the engine will still
wear out if you start the car frequently.  (Please forgiven the typist if this
does not quite make sense.  The mechanic does not type.)

Besides mileage, oil also goes bad just by coming into contact with air.  So
if you had your oil changed, then didn't drive the car for a full year, the
oil might need changing anyway.

The standard for oil changes used to be 3000 miles or 3 months.  More
recently, engine and oil improvements, coupled with marketing ("needs less
maintenance!"), have resulted in 7500 miles/6 month schedule.

Argh, my car is definitely due for an oil change, I've got to get off my duff
and do something about it.  :(

The manufacturers, for 1 or 2 years have put 7500 mi in their manuals.  Most
if not all have gone back to 5000.

My neighbor has decided to change it every 3000 miles, to be sure.

Guys,can we talk about trains in this conference?I would like to know which
is the fastest train in the world?Which is the most luxurious rail service?And
I heard that in the US,we have a coast-to-coast rail service?How many days
does it take?Is there a US-Canada rail service?How would it be if the US and
Asia were connected by the Bering strait by a rail service?
I am really a rail entusiast.Pl

You just missed a great lecture on land use and public transit.  In Karlsruhe
they came up with a vehicle that can double as fast long-distance train and
city tram, and it is very heavily used now.
Why not start a separate item here.  (Type enter, return, then your idea, .,
and the word Trains, and Y for yes).

A train connecting the US and Siberia probably wouldn't make much economic
sense, considerign that there is pretty much nothing in Siberia.  If I
remember correctly, there aren't even roads in much of Siberia.  I suspect
that that's the sort of trip where airplanes make a lot more sense.

Please make further contributions on trains to new item 103, I will be looking
forward to reading it.

I change my van's oil every 3,000 miles.  It's an aircooled Volkswagen, and
they're hard on oil due to high running temps and the fact that the total
oil capacity is only 3.5 quarts!  I can tell the difference between new and
old oil; the oil pressure takes longer to build after starting the engine,
with old oil.  With fresh oil, almost as soon as the engine fires the oil
light goes out; after a few thousand miles it takes a few long seconds to
flicker off.

Depends on crud or how you've cleaned the screen filter is my guess.  The
thing in oil that wears out is the additives, not the oil.

My suspicion is that the additives that make it a multiviscosity oil start
to boil off, making it thinner.  But it could be the filter filling up, I
suppose -- this is a '75 van so it has a full-flow oil filter as well as a
screen.  I've never cut open an old filter to see what it collects.

I suspect  that your VW van has some miles on it being a '75.  As engines
wear, more and more gas gets past the piston rings, thinning out the oil
with time.  You can get a relative idea of viscousity of new and old oil
simply by dropping a marble into the glass of new and old oil at the same
temp. and seeing which marble sinks the fastest.

You may be right -- tho bear in mind this is not the original engine.  It
was rebuilt about 60,000 miles ago.  That doesn't mean gas isn't getting
into the oil, of course.

Once-upon-a-time oil was marked as, e.g., "For service SC, SD, SE or MS."
I never did know what that meant...but I just recently noticed these
codes are not appearing on bottles of oil, but rather they read "API
service SJ/SH". What does all this mean (and why)?

(The oil change interval for my 1986 Subaru was specified as 7500 miles,
which has gotten the engine to 172,000 miles, so far, with a current rate
of consumption of oil of about 1 quart per 1000 miles.) 

I don't know what all the letters mean either.  I do know that if I compare
a bottle of store brand oil to a bottle of Pennzoil or Quaker State, the
store brand has a lot less letters on the label.  For this reason, I avoid
store brand oil for any service more challenging than lubricating lawnmower
engines.

I think I read somewhere, perhaps on a bottle of SJ rated oil, that SJ rated
oil is suitable for anything rated SA or whever they started up to SJ.  SH
would be suitable for all of those except SH, and so forth.  I have no idea
if that's correct or not.

That's my impression, too.

Oops, by response should have said "SH would be suitable for all of those
except SJ," rather than what I typod.

That doesn't explain why it says "API service SJ/SH" - why not just "SJ",
if that were true?
 
However, again, it turns out the Big Brain, also known as the WWW, is
better than all our little brains combined. The story is told on

http://www.api.org/programs_services/quality/oilchart.htm

except for MS. I still don't know what MS means.

If you don't have WWW, SJ is "For all automotive (gasoline) engines
presently in use."  All earlier Sx designations are obsolete. And
would you believe that "SI" is omitted to avoid confusion with the
symbol for "metric" units? The prefix "C..." is for diesel engine
oils.

MS is for microsoft service.

Response not possible - You must register and login before posting.

- Backtalk version 1.3.30 - Copyright 1996-2006, Jan Wolter and Steve Weiss