Oil change intervals

Oil change intervals are often discussed here. A study was done by
the CA Department of Toxic Substances Control. Shows that most of us
are changing too soon, wasting money.


http://www.dtsc.ca.gov/TechnologyDevelopment/OPPTD_FLY_High-Efficiency-Oil-Filters.cfm

Oils, filters, engine design has advanced considerably yet the oil
change places still try to sell you on 3000 miles. I'm still
advocating 7500 in most cases (per the manufacturer) just to avoid any
warranty hassles if anything comes up.

 

I,ve always figured $30-$40 for oil/filter every 4000 miles is a darn sight
cheaper than risking a new engine every 80,000 miles.
John

 

A lot of people figure that way. Your money, your choice, but it is
not needed. How many people do yo know that have had oil related
engine failures in the past 20 years? Probably none.
I'd agree with your idea, but I've put up to 180,000 miles on engines
with a 7500 mile change interval. Never a problem.

Take $35 a change at 4000 versus 800 miles. You did 20 changes while
I've done ten. That is $350 I have to spend on vacations, tools, beer,
whatever.

 

That is what those selling oil want to you think. The reality is that
with today's engines (no lead in the gas, tight tolerances, much less
excess fuel being burned, etc.) there is no risk to the engine with
changes at 5,000 to 10,000 miles depending on driving conditions. So,
you are spending extra money for NO reduction in risk to the engine.

Actually, I would argue almost the opposite today. By using more oil
filters per mile, you are taking more risk of getting a defective
filter. And each change carries the risk of human error in replacing
the drain plug and oil filter and either done improperly risks loss of
oil and subsequent catastrophic engine failure. My father had an old
filter gasket get left on the block and the new filter placed over it.
It started to leak and fortunately he caught it before it ruined his 454
Chevy engine. That would have been an expensive repair indeed.

So, I believe that more frequent changes today in all likelihood
increase the risk to your engine rather than reduce it.

However, I also admit to having the same irrational concerns as you. I
use Mobil 1 oil, but still change my oil at 5,000 mile and 10,000 mile
intervals. I use the former for engines under warranty and typically up
to about 100,000 miles unless, like my truck, they are not driven often
(5,000 miles per year on my truck). For cars driven a lot (my wife's
minivan), I change at 10,000 mile intervals. I suspect even my 5,000
mile intervals are conservative, but in the case of my truck this is
still only one change a year and time is a factor also.

The other reason I use 5 and 10 rather than 7.5 is that I can easily see
when the next change is due. With 7.5 you have odd intervals like 22.5
and 37.5 and they just aren't as easy to catch by eye as are 5, 10, 15,
20, etc.

Matt

 

<snip>

Well, I used to change my oil every three months, because I
didn't drive 3K in the same period or less. Since many of my
vehicles were given me by somebody who wouldn't change the oil
even yearly (10-15K, I figured it was good to "de-toxify" the
engine anyhow <g>.

Some of my high-milage cars would dirty up the oil pretty
quickly from piston blow-by or whatever. The two I have
now,though the oil is still clear when I change it at three months.
So now, I'm not seeing too much point in changing my oil every
three months, so I do it every six. I'd say I put 1-2K miles per
year on each car at this point.

Any comments on letting the oil "sit" in the engine? I know
water can condense in the crankcase, but that's going to happen
whether you change the oil or not; I try to drive each car a
reasonable distance each month so the motor can be fully warmed
up for an hour or two.

The 2002 Sonata I would be more willing to invest the money for
oil changes. The 1992 Sentra with 177K on it, I suspect was
driven for 2-3 years (about 40K) without any oil changes and it's
still running. I suspect it will still be running when I send it
to the crusher because the body has totally rotted through.

 

Interesting that you replied to my post, but did not include anything
that I posted.

Yes, a worn engine will dirty the oil faster, but the color of the oil
is not a good indication that it is ready to change. Oil can be quite
black and still be doing its job well.

As opposed to taking it out of the engine? I'm not sure what you mean
by letting it sit. Do you mean not running the engine at all? If you
plan to leave the engine in storage for a long period of time (more than
a month or so), then I would put in fresh oil and run the engine briefly
to circulate the fresh oil through the engine. Leaving dirty oil in the
engine for a long time will allow the acids formed from combustion to
start corroding internal parts. Fresh oil helps slow down this process.

This is precisely why changing the oil every 3,000 miles is such a
waste. Modern engines invariably outlast the car they are in, unless
you live in the desert. And even then the sun usually trashes the paint
and interior parts long before the engine dies.

Matt

 

I originally left more of the previous post, but wound up
snipping it...

Well, I'm not *storing* either car...I'm just not *using* them
very much. Given the amount I drive each car (1-2Kmi yr.) should I:

1. Change the oil every three months, even though it's like new?

2. Change the oil every six months, even though some acids may be
sitting in the engine?

3. Change the oil yearly, because I'm not driving the car enough
to create acids in any appreciable quantity?

Yes, three months seems wasteful. Six months seems a good
compromise, but I don't know how much acid would build up over a
year, even though it would logically be less than the levels most
people would have on an average.

 

I would probably go 6 months and depending on how you rack up the 1-2K
miles a year, I would consider 12 months. My last two motorcycles
(1200cc touring bikes) had a mileage interval and a one year time
interval and their engines are very similar to automotive engines (4
cylinder, liquid cooled, etc.).

If your mileage is accumulated by driving less than 5 miles each day,
then I would change at no more than 6 month intervals and even consider
staying at 3 months. If the mileage is accumulated by driving 30 miles
once a week, then I would go the full year.

The bigger concern I believe is running the car often enough to burn off
the moisture in the oil.

I think the acid build-up will depend on your driving regime as
mentioned above. If you have two cars and are driving this little, it
might make sense to consider selling one and driving the other twice as
much!

Matt

 

It always sounded strange to me the frequent oil change that usually
U.S. people do.
Here in Europe Hyundai says to have oil change in his vehicles every
15.000 Km (a bit less than 10.000 miles) or once a year, while other
brands (like Bmw) , using long life oils , tell to change it every
30.000 Km. (about 18700 miles).
Considering also that here we have smaller engines (that are subject
to more fatigue), change every 4000 miles are really a waste, unless
to use a very bad oil.

Zotto

 

Truth be known I agree with you re it being excessive. The amount of debate
though makes me cautious. Perhaps overly so. There is a website titled "Bob
is the Oil Guy" (www.bobistheoilguy.com) where there is much discussion re
oils and how much zinc etc has been taken out of modern oils. How the layman
works out the correct answer????. Probably placebo effect but I,ll stick
with the more frequent oil changes.
John

 

I think the relative high cost of lubricating mineral and of late synthetic
oils here in Europe compared to the low price in the US makes oil changes a
cheapish option for the folk in the US to change. It is after all is the
lifeblood of and engine and its cost is minute when compared to a
replacement or engine overhaul. Renault use a 20,000 mile oil change
interval - or two years- in the UK I believe.
I think the question should be asked if the high cost of premium synthetic
oil in an everyday engine is worth the cost when compared to a cheaper but
more frequent mineral oil change. Myself, I opt for more frequent lower
cost semi synthetic oils.

Gio