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One of the most common tasks to perform is replacing your engine oil.
Frequent oil changes are supposedly the most important thing you can do to
maintain and prolong the life of your engine. With the better oils that are
available today, the requirement for frequent changes is diminishing. Even
though BMW now recommends oil change intervals that are much farther apart
than in the past, I usually recommend that you keep the changes under the
5,000-mile limit. If you don’t drive your car too often, you should change
the oil at least once a year to keep things fresh.
The first thing you
need to do is to make sure that you have everything that is required for the
job. Nothing is more frustrating than emptying your oil, only to find out
that you don’t have a replacement filter or enough oil. You will need an oil
filter, a wrench, a roll of paper towels, a very large oil pan or bucket,
and between 4-7 quarts of oil. The E30 cars require between 3.5 - 4.2
quarts, and the E36 cars require 5 quarts for the four-cylinder cars, and
6.0-6.5 for the six cylinder cars. You'll also need a 17mm or 19mm
wrench to remove the drain plug from the bottom of the engine sump.
Start by driving the car around, and letting it heat up to operating
temperature. You want to empty your oil when it’s hot, because the heat
makes the oil flow a lot easier, and more particles of metal and dirt will
come out when the oil is emptied.
Once you get the
car parked, place the oil pan bucket underneath the oil tank of the car. At
the bottom of the engine sump there is a plug that is used for draining oil
(Figure 1). Remove this plug carefully, and make sure
you have a very large oil pan—about 7-quart capacity—under it, with a drip
pan under the oil pan in case you underestimate. The oil will be very hot,
and will empty out extremely quickly, so be careful not to burn yourself.
There will be no time to grab any more buckets or oil pans, so make sure
that the one you choose is big enough.
This is a good
time to remove the oil filter. You want to make sure that you remove the
filter with the oil pan still under the oil tank because the oil filter is
full of oil, and this oil will have a tendency to drip down out of the
filter into the tank and out the drain hole. On E30 cars, the filter is a
complete unit with a outer metal housing. This filter should only be
screwed on finger tight, but you may need a filter wrench to remove it. If
the filter is really on tight, you may need to resort to more drastic
measures. One sure-fire way to get the oil filter off is to poke a long
screwdriver through it and use the handle of the screwdriver for leverage.
It doesn’t matter that you are destroying the filter, because you are going
to install a new one. Be aware, though, that this method will leak oil out
of the filter into your engine compartment, so have some paper towels handy.
On the E36 cars,
the filter is a cartridge-type filter which is contained within a metal oil
filter housing (Figure 2 or
Figure 3). There is a cap that is located on top of the housing
(it may require a small socket, or a large one depending upon your year).
Remove the top (Figure 3 or Figure
4), and underneath you will see the cartridge filter. Simply
remove it from the oil filter housing (Figure 5,
Figure 6, Figure 7,
Figure 8 and Figure 9).
Have plenty of paper towels on hand, as oil will spill from the filter if
you're not careful.
While all of your oil is
draining, take the plug from the engine, and carefully clean it with a paper
towel. The plug at the bottom of the engine is magnetic, and attracts all
the little bits and pieces of metal that get trapped in the engine oil.
When both plugs are clean, replace them in the car with new metal gaskets
around the plugs. If you don’t use the gasket, they will leak oil. Torque
the two plugs to 25 Nm (18 ft-lbs) for the 17mm or 60 Nm (44 ft-lbs) for the
19mm drain plug.
Now head back into
the engine compartment, and install the new oil filter (E36 Filter -
Figure 10). For the E30 cars, install the oil filter
with the seal wet—wipe a small bit of oil on a paper towel, and use it to
make sure there is oil on the seal all the way around the filter. Screw on
the filter and make it snug tight. No need to use the iron grip of death
when tightening the oil filter—these don’t have a tendency to leak.
For the E36 cars,
you should clean out the inside of the oil filter housing before installing
the new oil filter cartridge. In your oil filter kit, you should also
have two o-rings and a replacement copper gasket for the long bolt that
attaches the top of the housing (early E36 cars). Replace the o-ring
at the bottom of the long bolt (Figure 11), and also
replace the large o-ring underneath the canister top (Figure
12). Insert the new filter into the housing (Figure
13), and reinstall the long bolt and the canister top. Tighten the
top of the canister to 25 Nm (18 ft-lb).
Now it’s time to
fill up your BMW with motor oil. A lot of people aren’t really sure what
motor oil to use in their car. Traditionally, the characteristics of motor
oil were linked closely to its weight. Heavier-weight oils protect well
against heat; lighter-weight oils flow better in cold. In general, if you
live in a cold climate, you should use a 10W-40 or similar oil. This oil is
a 10-weight oil that behaves and protects against heat like a 40-weight oil.
In warmer climates, you should use a 20W-50 oil. This oil doesn’t flow as
well at the colder climates, but gives an extra “edge” on the hotter end.
The question of
whether to use synthetic or traditional “dinosaur” oil often comes up among
car buffs. Consumer Reports (July 1996) ran an extensive test on the
two types of oil, altering amongst many different brands. The testers
installed freshly rebuilt engines in 75 taxicabs, and then ran them through
the harshest conditions on the streets of New York City. Placing
different brands, weights, and formulations in the cars, they racked up
60,000 miles on the engines, tore them down, measured, and inspected the
engine components for wear. The oil was changed at 3,000 miles in half
of them, and the rest were changed at 6,000 miles. results: regardless of
brand, synthetic or dino, weight, and oil change interval, there were no
discernable differences in engine component wear in any of the engines.
Their conclusion? Motor oils and the additives blended into them have
improved so much over the years that frequent oil changes and expensive
synthetics are no longer necessary.
Still, some people
swear by synthetic oil. In practice, I don't recommend using synthetic oil
if you have an older car with old seals in the engine. There have been many
documented cases in which the addition of synthetic oil has caused an
otherwise dry car to start leaking. If you own an older BMW that doesn’t
have fresh seals in the engine, I would stick to the non-synthetics.
Fill your oil tank
from the oil filler hole in the top of the valve cover (Figure
14), located in the engine compartment. Add about 4 quarts
to the engine, and check the dipstick. Continue to add about a half a
quart at a time and keep checking the dipstick. Fill it up until it
reaches the top mark of the dipstick - the engine oil level will
automatically lower when the oil filter fills up with oil. Make sure
that you put the oil filler cap back on the top of the valve cover,
otherwise, you will end up with a messy engine compartment when you drive
Now, start up the engine
with the hood open. The oil pressure light should stay on for about a
second or two and then go out. Hop out of the car and look at the
engine compartment, then take a quick look underneath the car. Verify
that there's no volumes of oil seeping out of the engine. Now, take
the car out for a drive and bring it up to operating temperature. Shut
the car off and then recheck the oil level (careful, the car will be hot).
At this point, I like to top the oil off at the top point on the dipstick.
Make sure that you dispose of your old oil at a respectable recycling
Well, there you have it - it's
really not too difficult at all. If you would like to see
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