Determining oil change intervals via analysis

eh? we're discussing wear. tribology is the science of wear and
lubrication. your problem with this subject seems to be that of
inconvenience, not lack of relevance.

 

so how does that simplistic straw man get around the point i raised,
i.e. "where you're getting confused is reading glib little articles on
the net that cleverly avoid the distinction between phrases like: "wear
is reduced" and "wear is within acceptable limits"? [rhetorical]

oh dear. do you really think that putting words in someone's mouth,
then using that as a platform for criticism is not childish and utterly
transparent?

bottom line matt, i'm not going to waste any more time arguing with you.
having just googled a bunch of your other threads to see what kind of
person you are, i see you're only interested in poisoning the well
and ad hominem rather than contributing any useful data and i won't play
that game. doubtless you'll "respond" by bleating some toxic criticism
that'll contribute nothing to the subject in hand, but i won't care
because i'm not going to read it. have a great life.

 

I knew a fair bit about tribology when I was working with magnetic disk
drives and recording heads many years ago, but that isn't relevant here.
I've seen very few areas where accurate prediction of wear has been
made. Often it is reasonably possible to predict that particles above a
certain size will cause nearly catastrophic failure, but I've never seen
a refereed paper that predicted auto engine life as a function of
frequency of oil changes or particle size distribution in the oil. If
you are aware of some, please post a reference. Shouting "tribology"
isn't data, isn't meaningful and thus isn't relevant to the discussion
at hand.

Matt

 

Yes, I have a history of challenging people who make claims to back up
those claims with data. Some are able to do so, but most are like you.
They get huffy and go away. Your choice.

Matt

 

isn't amazing how 2 people can read the same article and perceive two
different meanings? when i read "We saw no meaningful differences." and
"we noted no benefit", i don't perceive any statistical significance
testing, data tables, or results, i perceive conclusions. and when we
have comments like "Generally, we noted as much variation between
engines using the same oil as between those using different oils. Even
the engines with the most wear didn't reach a level where we could
detect operational problems." there's three relevant items you seem
to be missing:

1. again, there's no measurement data.
2. there are no yardstick defined.
3. where's the investigation of variance between engines? there's
/always/ a reason for that.

in reality, if the objective of this piece is to measure wear, the
yardstick is not "well it seems to work ok", the yardstick is thou or
mm, but it's absent. we're not even given wear as a percentage of
acceptable wear tolerance which is much simpler to tabulate for the
layperson - which is the /minimum/ i'd want to see. instead, all we're
given is this allusion to a testing protocol and conclusions, i.e. "take
our word for it". and you accept that?

and while on the subject of measurements not made, why not measure the
piston ring gap? rings are the most susceptible to wear with the
temperatures and sliding speeds they achieve, so why avoid something so
relevant? if i run two different brands of oil in my honda and one has
a high burn-off rate, but the other is zero [i give this example because
it's something you can test for yourself], are you going to tell me
there's no difference in oils? and if there /is/ a difference in oils,
are you then going to argue that the oil with the highest burn rate,
i.e. the one that scorches off the hot stuff more easily, is offering as
much protection as the one that doesn't? measure that ring gap and give
us the data!!!

i've never argued that so don't put those words in my mouth.

 

I agree with Brian and you. Yet the most heated arguments here (and
elsewhere!) are about oil. And they keep popping up over and over. WOW!!

I think much of the arguments are caused by people thinking in terms of
"absolutes". Even with impeccable lab testing, there are rarely absolute
conclusions with so many variables involved.

When it comes to oil, I think in terms of "The existing body of evidence
shows that using X product and changing at Y frequency will probably be
fine". I'm definitely not going to spend more than my car is worth to prove
things to 99.997% certainty!


Why not say:

Dino oil... Change at 3000-5000 miles.
Syn oil... Change at 4000-7000 miles.

Anything in this range has proven acceptable practically forever. Everyone
should choose their product and comfort level, and relax!

 

ah, the old inference argument! why not direct contradiction?

er, consider two things:

1. if a wear rate is X for a given lube regime, and service life is Y,
we can figure out what the service interval needs to be.

2. now, if you want to alter Y, what do you need to change in the above?

well, you keep on doing what you want to do. i'm just an anonymous
troll that can't be bothered to spoon feed people stuff they don't want
to hear. but if you care to dabble in the high mileage used car market,
you may get to be more familiar with the direct results to the concept
outlined above.

 

You have absolutely no proof of that, therefore you cannot claim that.

Until you have proof, you must shut up. That's the new rule around here.[/QUOTE]

I hope you were looking in the mirror when you said this. You have yet
to provide any evidence to support your claims.

 

There's one really good reason, Hyundai recommends changes every 7500
miles with "dino" oil. THEY should know what's best for THEIR engines.
If people would just use their heads and follow Hyundai's
recommendations rather than insisting on adding myth and folklore to the
mix, we wouldn't be having this debate.

 

Definitely! The problem is that the motoring public has been
brainwashed by that 3,000 oil & filter mantra. Too bad also that the
service personnel at the dealerships are bucking the change as well.
Within the last 18-24 months I read articles indicating that GM is going
nuts trying to get their dealers to go along with GM's oil change
recommendations as indicated by the on-board computerized oil change
indicators now on most of their better vehicles.

Granted, it's not a chemical analysis of the oil but it tracks the kind
of usage the oil is being subjected to. You just know they have a
margin of safety/error built into their calculations, just as they did
when they stood proudly by that "Change it every 3,000 miles or else!"

Speaking of which, I always changed filters with the oil - even when I
was doing my own changes. Browsing through the manual for my new Accord
EX V-6 it appears that Honda wants an oil change ONLY at ~10,000 (or as
indicated by the oil life computer) but no filter. Am I reading that
correctly?

 

The auto makers lose either way. If they recommend 3,000 mile changes,
they get accused of being in bed with the oil companies and if they
recommend 10,000 mile changes they get accused of wanting you to wear
out your engine too soon so they can sell you another one.

I don't know as I don't have an Accord. One was enough for me.

Matt

 

Because it isn't true.

 

So you have no homeowner's insurance? No car insurance? After all,
your house will never burn down and you don't ever plan on getting into
an accident, therefore you don't need those things.[/QUOTE]

However, if you have a bank loan for that, they require it..so it is
needed.

 

And the rest of the world too.

 

There is not shortage of data.

 

Uh...this is not true! Our dealership goes along with GM's extended
oil change intervals. It's not us that is the problem, it's the customers.
They don't like the extended oil change intervals. A lot of the Caddy
owners are older folks who are used to their 3 month/5000 kilometer
service intervals. Cadillac owners get free oil changes, but "only" when
the oil change light comes on. We get a lot of these people just paying
for an oil change because they don't want to wait for the oil change
light to come on.

Personally, I prefer the old 3 month/5000 kilometer interval for my
own cars, but I will say that I've seen nothing in the last 10 years that
indicates that extended oil change intervals do any damage to engines.
Engine oil is so obviously better then it used to be. We almost never
see engine failures that were rampant in the 80's....rod bearing, main
bearing, crank failures...cam failures...etc.

Hello. Why are you questioning the manufacturer's recommendation?
"THEY" should know best about "THEIR" engine...right? Or are you
just a little bit uncomfortable because "you've" always changed the oil
filter with the oil change? See....even you find it hard to switch over
to a new way of doing things.

I've always driven old 100 dollar beaters. I've often just spun on a new
oil filter instead of changing the oil, as they burn/leak so much oil that
the oil is constantly being replenished. I've never had an engine failure
yet.

Ian

 

I would be MUCH more comfortable if I knew that the recommendations were
coming directly from engineers, unsullied by the hands of marketing
people.

Marketing people have one goal: sell more cars. To do that, they make
the cars more attractive to the consumer. To make the cars more
attractive, they make sure they can fill a positive checklist with as
many checkmarks as possible, to compete with the next guy. One of those
checkmarks is, for example, "100,000 mile tuneup interval". Another
would be extended time/distance oil changes.

When I read the owner's manual for some of this, I have no idea if the
recommendation came directly from engineering, directly from marketing,
or is somewhere in the middle.

 

A lot of my post was tongue in cheek, poking a bit of fun
at some other posters.

The extended oil change is a marketing thing for GM. Our District
Service Manager pushes this because it looks good for GM to
be "green", make the vehicles "appear" as though they are
"maintenance free"....etc. Of course it conflicts with the dealership
in that we like to get the vehicles in more often. GM also would
be quite happy if the vehicles stay out of the dealerships, as we
end up finding all sorts of problems with the vehicles which are
still covered under warranty. GM is not that interested in fixing
problems during the warranty period.

Ian

 

somewhere in the middle. the engineers know the wear rates, the
marketing folk know their competition, and they both figure out the
place they need to be. in the current market, very few people keep a
car more than 100k, or not first owners, so that's where the attention
goes - for every manufacturer in the world. [the small euro stuff
concentrates only on the first 100kkm and manufacturers actively seek
accelerated failure rates after that!] if you have a motor that
routinely makes 300k on 7.5k change intervals [honda], why not bring the
life expectancy down by extending change interval to 10k or even 20k?
the motor will still make 100k easily, the marketing folk are happy, the
first owner is happy, and ultimately honda is happy because at the end
of the day, they get to sell more cars.

it used to be that the way the japanese broke into the market was by
quality & longevity because it was a differentiator, but today their
position is so solid, people will still buy their cars even if life
expectancy drops in half because domestics are /still/ so much worse!
timing chains anyone?

 

Most people buy insurance to protect themselves from financial loss. I would
consider a destroyed engine a "financial loss". Therefore, if frequent oil
changes were instrumental in preventing engine failure, they would be good
insurance.

Dave