How to do-it-yourself instructional on selecting the correct engine oil.
Explains API Service Classifications, Viscosity, Synthetic and Multi-grade
- Today on Repairs101 I’m going to show you
how to choose the right engine oil for your vehicle.
Alright, here we go. Today on Repairs101 I thought I’d try and
answer the question that I get asked more than any other question - and that
is “What kind of oil should I put in my engine?”
Now it’s a really good question and it’s really worth looking
into. So today I thought I would try and teach you how to decide for
yourself what kind of engine oil to put in your engine. Using the wrong
motor oil can lead to poor performance, premature wear and ultimately it
could lead to failure.
- Here’s the chart given in my Buick
Century’s owner’s manual. You can see, very similar in the owner’s
manual for my Blazer.
- So maybe the first question you’ve got to
ask yourself is “What am I burning? Am I burning gas or diesel?”
There’s a big difference between oils designed for gasoline engines and
oils designed for diesel engines.
- So the API – the American Petroleum
Institute is the system that’s in use here in Canada and the US. So the
API classifications start off as SA, then SB, SC, SD… you get the idea,
right? Around the world there are other systems in use. OK you can see here
right in the opening pages of the book – of the service manual - you can
see that they are telling you that they want engine oils that are labelled
by the API.
- OK so they call this “the API Gasoline
Engines Starburst”. Oils made specifically and exclusively for gasoline
engines will have the starburst on them.
- OK now this little symbol here is called
“the API Donut” and this donut gives you all the information you need to
know about the oil. It says that it’s API service SL, in the middle of the
donut it says that it’s SAE 5W-30 viscosity and underneath it tells you
that it’s an energy conserving oil.
- Here’s a list of API Service
Classifications for gasoline engines and here’s a list of API Service
Classifications for diesel engines. Now, of course the reason I’m flashing
through this quickly is because, for most people, it’s really not that
important. A real Gearhead might want to study these charts and understand
them. Now most people just aren’t going to need to know every service
classification on the chart, OK? We’re going to go to the store we’re
going to pick up what’s on the shelf. It’s going to be fairly current if
not the most current oil available and it’s going to match our fairly new
to used vehicles.
- Whether you think the “S” is for
“Spark” or “Service” and whether you think the “C” is for
“Compression” or “Commercial” – it doesn’t matter, as long as
you learn that “C” is for diesel burning engines and “S” is for
gasoline burning engines. If you have a brand new vehicle I definitely
recommend checking and seeing that the Service Classification called for by
the engine manufacturer matches the service classification of the engine oil
you intend to use.
- OK so viscosity – now that’s another
issue. Viscosity is the measure of how thick an oil is. Think of molasses in
February, now that’s going to be really thick. Right? Whereas water is
thin. The lower the number on the viscosity scale – the thinner it is. So
it’s very simple. So a five weight oil is going to be very thin compared
to a forty weight oil, say. So
keep in mind that when you’re considering viscosity for your vehicle,
really what you’re asking yourself is “Is it going to be thin enough to
start in the coldest conditions that it’s going to be exposed to?” So
for instance, if you’re in the Yukon at Christmastime you’re going to
need thin oil – you know a five weight oil or even a zero weight oil. If
you’re in an Equatorial climate then for sure you’re not going to really
need anything very thin. You could go with a straight forty weight oil or
straight thirty weight oil probably and have no problems ever starting it
because it’s not going to be thickening in the cold.
- So Multi-grade oil is what they’ve come up
with to address the problem of “cold starts” and then being thick enough
to protect the engine when it’s hot and running. When it’s cold it
behaves differently than it behaves when it’s hot and the way they do that
is they introduce a polymer into the oil in order to make it behave
differently at different temperature ranges. For instance, when it’s cold
it will be much thinner than when it’s hot. Which is counter-intuitive, I
- So what they’re saying here is if it’s
below zero degrees Fahrenheit you’re going to need a 5W-30 oil
and if it’s above zero degrees Fahrenheit you’re going to be OK
with a 10W-30 multi-grade oil. OK over on this page we’ve got another
viscosity chart and this time it’s given like a bar-graph.
- So most everybody uses multi-grade oils in
the vehicles these days with the exception of “extreme service” and
collectors you know, the real hardcore Gearheads, they’re going to want to
use single weight oils because they’re changing their oil three and four
times a year and they want to make sure that – no matter what the
conditions are - they’ve got the absolute best performing oil in their
crankcase. Most people are going to fall into the lower one or two of these
categories and be wanting to use either single-weight oils from this column
here or multi-grade oils here and here, OK?
- Compared to conventional oils, synthetic
oils last a lot longer, they can withstand a lot more heavy duty
applications, extreme duty applications, more continuous service. They’re
better in turbo-charged systems, super-charged systems – anywhere again
where there is extreme service. OK some examples of extreme service would be
– continuous service. Say an engine that’s running twenty-four hours a
day like a Taxicab or a Police vehicle. Say a forklift that’s running
commercial duty. Race-cars, high performance vehicles,
or how about say a tugboat that’s running twenty-four hours a day
pulling a load through the inside passage. Something like that, you know?
That’s extreme service.
- Now synthetic oils will last longer because
they resist degradation through oxidization. In other words they don’t
oxidize quite as rapidly as conventional oils.
- OK so after you decide what you’re burning
– gas or diesel – and which Service Classification of oil you need –
is it a “C” class oil or an “S” class oil? Then the last thing you
want to know is what viscosity you want and the only thing you have to ask
yourself is “How cold is it going to get when I start this thing?” And,
like I said, the lower the temperature, the lower the number viscosity you
want. And if it’s real, real cold out there you want something as low as
5W or even 0W to get her started.
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