DIY Oil change in a 2002 Subaru Forester?

[M.J.]

I change my oil at regular intervals, take it to the recycling tank
without really "looking at it", and I'm done with it. It held the "crud"
in suspension long enough to get it out the engine,

How do you know it got ALL of the junk out, and not deposited most
of it on your engine internals? Do numbers from oil analysis tell you that?

..... and therefore, I consider it "did its job." From there, who cares?
My cars won't last any longer or die any sooner because I looked or
didn't.

Well, good for you, I guess.

M.J.

 

[Rick Courtright]

How do you know it got ALL of the junk out, and not deposited most
of it on your engine internals? Do numbers from oil analysis tell you that?

Hi,

There is only ONE way to get ALL the crud out: tear down the engine and
clean all the parts!

Short of that, there will ALWAYS be a certain amount of crud deposited
somewhere in the engine. The places it's going to build up most,
assuming regular oil changes, will usually be benign "nooks and
crannies" where oil splashes and lands, then sits w/o being able to
circulate quickly. With MOST engines, this is NOT a problem (however,
there ARE some engine designs that are problematic, but they're
problematic REGARDLESS of the oil being used. One case in point being
the infamous Toyota "sludge engines." Not to single out Toyota--many
other mfrs have had one or more of these "problem child" engines.) As a
general rule, those places that have either pressurized oil flow, or a
lot of oil flowing over them all the time, like return galleries, will
show the least buildup of varnish or other crud. That's simple enough to
see in a teardown.

What does oil analysis do for you in this regard? It simply tells you
WHEN you need change your oil because it's reached the maximum level of
contamination it can handle w/o causing "excessive" wear or damage to
your engine. I say "excessive" because the engineers design a certain
amount in when determining THEIR idea of the life expectancy of the
engine. By changing oil and filters far more frequently than suggested
by the owners manual, we MAY be able to cut the wear factor far below
the design level. And then again, we may NOT. This is ONE of the reasons
you will probably see far more of the "high mileage" engine reports (a
quarter million miles or more is a number that sticks in my mind) are
from guys who change at more frequent intervals. But the frequency of
oil changes is only one of many factors in engine longevity, so it can't
be pointed to as THE reason a particular engine lasted a certain number
of miles.

So while the best way to achieve dependable oil analysis figures is
probably to start with a "new" engine (crate new or rebuild new) and get
a baseline figure, then have a series of oil analyses done at differing
intervals to determine what the best "average" interval is, you can
start at any point and at least have a baseline figure to use to
estimate your engine's condition. At first, while the engine's wearing
in, certain numbers will be high, then they'll usually stabilize, so you
can tell how far from a given number you've "strayed" which CAN be a
useful diagnostic tool if you're running a fleet. For the individual
owner, it's probably more a "feel good" thing, since most of us aren't
going to stop what we're doing and tear apart an engine when we see a
"high" number for say, a bearing material, indicating bearing wear.
We're going to watch the oil pressure gauge, and figure as long as it's
ok, that bearing hasn't worn badly enough to worry about.

This is why I suggested you siphon the "clean" oil off your specimen and
have it analyzed! Most of the contaminants that cause wear, the
particulates, will have settled out and won't be present in that "clean"
sample. Other items, such as metals, may or may not still be present.
But the analysis figures will tell you "change" or "keep" even so.

Another thing oil analysis will do is tell you what you're LOOKING at is
anything, or nothing, in the grand scheme of things. One of the things
your oil does is "clean" in the sense it carries crud to the filter to
be caught and held for disposal at the next change. One of the criteria
the engineers look at is the "size" of the crud, measured in microns (1
micron = .000001 m = .000039 in), and there are ranges to be concerned
with, ranges not to worry about. Most sources you can easily find
suggest most of the engine wear is caused by particles in the 5-20
micron range. A majority of oil filters on the market do VERY well at
removing crud above 20 microns, some do a pretty good job in the 10-20
micron range (brand and model CAN'T predict this! Only testing does--one
catalog number may be excellent, another barely passable), few do so
well below 10 microns or so. Why not? Engineers must balance flow and
pressure against efficiency. They CAN filter out much tinier stuff, but
then you'd be changing your filter every few hundred miles when it
clogged, and who knows how long your engine would last w/ the reduced
flow? So there's a balancing act involved.

Now to take this further, we have bypass filtration. A bypass filter CAN
get out extremely tiny junk but it can't flow much. So I'm gonna
illustrate why your "visual" estimation of how good a job your oil is
doing can be flawed.

Years ago the Frantz people introduced bypass filtration to the masses
with the "toilet paper" filter. The people selling these filters had a
neat visual aid they used to show people how well their unit worked.
They had a test bench set up with a container of clean oil, a pump, a
full flow filter and a bypass filter. There was a switch to put the
bypass filter in the loop or take it out.

They would start the machine, and you could watch the oil go thru the
full flow filter and the bypass filter. Since it was clean oil, it
wasn't an impressive sight at first. But then they would isolate the
bypass filter, and introduce a bit of carbon black to the "clean" oil.
Instantly it would turn jet black! And as it circulated thru the full
flow filter, there was NO change in color. Then they'd turn on the
bypass filter, and in a couple of minutes, the oil was back to being
"clean" again.

So the first thing that would go thru one's mind as they watched this
was "that oil is filthy" followed by "my oil filter's not doing much of
a job" and, the salesman hoped, you finished with "I'll buy one!"

But as I mentioned before, there's more than meets the eye! Carbon black
is LESS than 1 micron in size. So it's NOT a player in the wear
equations! But it certainly makes the oil LOOK bad! And, using your
visual "settling rate" estimation, it would stay "in suspension" for an
extremely long time simply because the mass of the particles is so low
it takes "forever" to settle out. Oil analysis would help you determine
if you're looking at actual wear particles, or just "carbon black" type
contaminants! One would dictate it's time to change your oil, the other
is strictly "fuggedaboutit" territory.

So "you pays your money, you makes your choices, and you takes your
chances!" IF you're blessed with the resources to take two IDENTICAL
engines, and run them under IDENTICAL conditions side by side where the
ONLY variable being changed is the oil being used, change intervals,
filter, or some other item, you can come up with decent data on what's
"best." Since the mfrs DO have these resources, and DON'T recommend any
particular oils or filters as a result of their testing, there should be
a lesson in there for us mere mortals who have to work hard just to have
one or two vehicles to drive! Otherwise, we're just arguing how many
angels can dance on the head of a pin... and that's why the man insisted
on "Show me your numbers...!"

Rick

 

[S]

Hi DJ!

Can anyone give me any tips or things to look out for when I do the oil
change? Also, any recommendations on after market filters and oil
products would be great!

Basically, just do it. It helps to be able to get under the car. 17mm
socket fits the drain plug, and I use a large pair of Channel-loc
pliers to get the filter. 4 bolts hold the splash guard in place, plus
a couple pesky plastic fasteners at the upper rear corners. Use a
small flat screwdriver to gently lift the center pin ~1/4 inch, and
then pull the whole thing out. It's easier the second time . . .
I like Castrol GTX in 10W30, and change filters every other oil
change, but I change oil at 3-4K mile intervals. I use either an OEM
filter, the "upgraded" Fram item, or, if I can find 'em, Purolator
"Pure-One" filters. Takes 4 quarts w/o filter change, 4 1/2 with.
(This for the SOHC motor; I _think_ the DOHC is the same, but ???)

ByeBye! S.


Steve Jernigan KG0MB
Laboratory Manager
Microelectronics Research
University of Colorado
(719) 262-3101

 

[Cam Penner]

Hi DJ!



Basically, just do it. It helps to be able to get under the car. 17mm

If you jack the car up, PUT SOME BLOCKS OR AXLE STANDS
UNDER IT before YOU go under it. Don't die doing an oil
change.

I've had some success at poking a hole in the filter with a
screwdriver and letting that drain before unscrewing it.
It at least changed HOW the oil spills onto my arm. I use
a Fumoto drain valve - and love it.

 

[M.J.]

If a particular type oil is behaving substantially differently than other
well known "good" oils after its has been drained out of the crankcase
chances are it was also behaving differently when it was in the engine.
Don't you agree?

The scientific process starts with observation, visual, and other.
Findings collected this way are a basis for forming hypotheses.
Hypotheses get proved or disproved by further testing.

So basically you are right, testing would be needed to establish for
sure that the oil was no good. I should't have stateted that the oil
IS bad, just that there are some preliminary indications that the oil
MAY BE utter crap.

Personally, when I see something fishy, I decide to optimize, i.e.
save on the cost of further testing and investigation, and I avoid the
product altogether, aware that there is a probability that I may be
wrong. You may call it I get spooked, or follow a "buyer beware"
approach, or something. By the way I think I behave like the average
consumer (?).

Just came from Walmart w few minutes ago, the oil brand is called
Accel, and there are several viscosities- I used 10w-40.

M.J.

 

[Rick Courtright]

I've had some success at poking a hole in the filter with a
screwdriver and letting that drain before unscrewing it.
It at least changed HOW the oil spills onto my arm. I use

Hi,

I've used the screwdriver trick, or a nail thru the end of the filter,
and as you said, you're mostly redirecting which part of your arm gets
burned! Another trick I've used that ~sometimes~ makes life painless is
to break the oil filter loose about one full turn BEFORE opening your
drain valve--not quite enough for oil to start leaking. Take off the oil
filler cap so you get lots of air thru the engine, then open the drain
valve. Once the oil's out of the sump and has drained a few minutes,
remove the filter. About half the time I can get the filter off w/o even
spilling a drop. The other half the time there's a little driposis, but
not bad. I don't know why it's a hit or miss proposition unless the
anti-drainback valve sometimes does a better job than other times?

It might be worth a try to see how it works on your engine!

Rick

 

[Rick Courtright]

Just came from Walmart w few minutes ago, the oil brand is called
Accel, and there are several viscosities- I used 10w-40.

Hi,

Does this oil have an API rating on the bottle? If so, does it have the
SAME API rating as, say Mobil 1, which I think most people would agree
is a "premium" quality oil?

If they both carry the same API rating, we know they both have met a
MINIMUM set of test requirements, and are therefore equal at worst. Now,
Mobil 1 MAY be far superior to Accel, but we CANNOT prove that without
scientifically valid testing protocols. Lacking those, any supposed
differences are anecdotal or advertising hype. So, you may OBSERVE that
your engine appears to be cleaner w/ Mobil 1 than with Accel (or any
other.) You then form your hypothesis that M-1 is the better oil. Now
the process DEMANDS proper testing to establish the validity of your
hypothesis. On this we agree.

Where we disagree is that you've initially tried to establish your
hypothesis (which MAY very well be valid, but we don't know!) as a basis
to describe one product as "crap" (or otherwise inferior) without
benefit of testing. My point has been, and remains, that the
manufacturers HAVE done the testing, and haven't found enough
significant difference to recommend one brand over another, AS LONG AS
each brand carries the recommended rating. I'm sure they've observed the
same things you have, but nobody's "shown us the numbers" to show that
observation carries much weight, if any, within the parameters they feel
are important.

A last note on "observations": the behavior of your oil outside of the
engine cannot be correlated to its behavior inside on its face. We could
come up with all kinds of scenarios, some of which would support your
idea, some of which would not. One, for example, that would not might
run like this:

We have two otherwise identical cars, and we fill one with 10W-40, the
other with straight 40 wt. We also have two extra quarts of each the
10W-40 and the straight 40 weight. We put one quart of each in the
regrigerator at, let's say, 35 deg F, for an hour, the other quart of
each goes outside and sits in the sun for an hour, and we send the cars
out to run 70 mph for that same hour. The average daily temperature this
time of year in my neighborhood is very close to 100 deg F. At the end
of the hour, we pour a little of each oil out and watch how easily it
flows. There is going to be a definite advantage to the multigrade that
came out of the fridge. There's probably also even a slight bit of
"advantage" in favor of the multi-grade that sat in the sun, though it
will be lesser. While we're observing that, the two cars come in and we
drain both engines simultaneously. Compare the behavior of the oils in
the engines to those sitting in the bottles. Notice a difference? We
could make up these scenarios all day. Again, how many angels can dance
on the head of a pin?

So "You pays your money and you makes your choices" on whatever makes
YOU happy, confident, whatever. You're free to think "my choice is best
because...." That's one of the benefits of having a competitive market
place to choose from, and that's about the last I care to say on this.

Rick