Details for Click & Clack.

Click & Clack
Talk Cars
“The Tappet Brothers’’

By Ray Magliozzi

Money Miser wonders how long
to wait between oil changes

Dear Car Talk:
I change the oil in our cars,
mainly because I’m too cheap
to pay what oil-change shops
charge. Is there any way to test
to see when the oil in a vehicle is
almost worn out? Our cars vary
widely in their use. One does a
daily 15-mile commute; another
goes 60,000 highway miles a
year; and a van goes 3,000 miles
or so a year, at times pulling a
small camper. Sometimes the
oil I drain looks like new. With
oils and filters being so good
these days, I’m wondering if I’m
wasting time and money. If there
were some litmus test for oil, it
would be helpful, rather than
simply going by miles. Thanks
from a fan for decades. -- Pat
There’s not really a good
litmus test, Pat. For ages, we’ve
always estimated with miles
and months. For a long time,
our recommendation was to
change the oil and filter every
three months or 3,000 miles.
But that recommendation is
completely outdated now.
With conventional oil, you can
go six months or 7,500 miles.
And with synthetic oil, you can
go 10,000-12,000 miles, or a
year. Some say more.
But now a lot of cars have their
own, built-in oil life indicators.
They work in different ways,
depending on the manufacturer.
Some use a direct measurement
of some kind, testing the
conductivity of the oil, the soot
concentration or the presence of
water. Other systems keep track
of your mileage, the number of
times you start the car and the
temperature conditions under
which you drive. They feed all of
that data into an algorithm, and
then tell you when it’s time to hit
Pokey Lube.

Those systems seem to work
well, and can help you cut down
significantly on the frequency of
your oil changes, based on real
evidence rather than guesswork.
So you might want to make sure
that your next vehicles have
those systems, Pat.
As for an aftermarket “litmus
test,” where you wipe some
magic test strip on the dipstick
and find out how much oil life
remains and whether you soon
will meet the girl of your dreams,
I haven’t found anything I’d
be willing to really rely on yet,
given that the downside is a
ruined engine. It’s just not a risk
I’d feel comfortable taking with
my own car.
If I were you, I’d switch to
synthetic, just to reduce the
amount of time you spend lying
under those three cars with
hot oil running down into your
armpit. And keep changing the
oil based on your best estimates.
After all, even several extra oil
changes over the life of a car are
cheaper than an engine rebuild.
Tom and Ray share secrets
on how you can save tens of
thousands of dollars on your cars
over the next 20 years in their
pamphlet “Should I Buy, Lease,
or Steal My Next Car?” Send
$4.75 (check or money order) to
Car Talk/Next Car, 628 Virginia
Drive, Orlando, FL 32803.
Got a question about cars?
Write to Ray in care of King
Features, 628 Virginia Drive,
Orlando, FL 32803, or email by
visiting the Car Talk website at
(c) 2018 by Ray Magliozzi and
Doug Berman
Distributed by King Features
Syndicate, Inc.


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