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These are just some notes about my most recent oil change
and some information about magnetic chip detectors.

The previous oil was Shell Rotella 0W40 run for 20 months
and 6000 miles. It exhibited no worrisome degradation
in that time. The oil came out black which is just a
sign that the dispersants are doing their job.

No makeup oil was required and there is really not a problem
with the time interval since the crankcase is basically a closed
container. If you wouldn't worry about oil aging in the jug, why
worry about aging in a closed crankcase?

The ambient temperatures during use ranged from -30*F to 100*F.


I gathered up the following materials and tools:

Castrol Edge 5W50
Mann 719/7 oil filter
Dimple Magnetic Drain Plug 14mmx1.5mm 24mm long

13mm box wrench
drain pan

If you use a large but low drain pan it is entirely
possible to change the oil and filter without lifting
the vehicle. Mine is lower than most X308's since it
has the euro spec sport springs and has sagged a bit
due to age.

- crank the front wheels all the way to the right

- break loose the drain plug without removing it.

- position the drain pan under the drain plug then finish
removing the drain plug and let it drop in the drain pan.
It is too awkward to try to control the plug due to
limited finger room.

- once the oil has drained completely, retrieve, clean
and reinstall the drain plug

- move the drain pan in position under the oil filter

- remove oil filter, it will be just above the front
arm of the lower control arm, drop into drain pan
and let oil drain from the filter adapter area

- lubricate face of the oil filter gasket with a
smear of oil and install, giving the filter a
further half turn after the gasket contacts the
filter adapter (pre-filling the filter is very awkward
with a side mount filter and the car on the ground)

- install at least 6 quarts of oil as a start

- check level with dipstick to ensure that the
oil is at or above the minimum mark

- prime the system by holding the accelerator pedal
to the floor which will inhibit the fuel injectors,
then turn key while stil flooring the accelerator pedal,
to the start position and crank for a few seconds. repeat.

- start vehicle normally ensuring that the oil pressure
warning light goes off within a few seconds. run for
30 seconds and turn off.

- check oil level using dipstick and top off as necessary

Most owners will want the oil at the full mark. Some
owners will want to run the 'silverstone' specification
which is one quart above the max mark.

If running the 'silverstone' spec, you will have to sneak
up on the fill because overfilling beyond the extra quart
would be really awkward. When using the dipstick
repeatedly during the last bits of filling it is preferable to
leave it out of the dipstick tube while adjusting since the
oil in the dipstick tube will get a chance to drain. It is
easiest to get a clean reading by pulling swiftly during the
first foot of movement so less oil stuck in the tube clings
to the dipstick.



DIMPLE MAGNETIC DRAIN PLUG

As an added precaution I chose to install a Dimple
magnetic drain plug.

The OEM drain plug is 14mmx1.5mm thread and 20mm
long at the shank.

The Dimple drain plug I selected is 5mm longer and
originally listed for Mercedes vehicles:

DRAINPLUGMAGNETS.COM

Since contacting the owner of Dimple, a listing for Jaguars
has been added on this page:

BUY HERE IF YOU KNOW YOUR PLUGS THREAD SIZE

The flange diameter and washer are smaller than OEM,
but it seals well. Some users may prefer to add a larger
diameter copper or nylon drain plug washer.

Dimple says their magnets are the strongest available
and high temperature rated. The strength claim is undoubtedly
true. On installation I found that it was necessary to carefully
center the drain plug due to the magnet wanting to just cling
to the nearest steel it could find. At least on the next drain I
can let it slide to the side and hang on to the pan instead of
dropping it in the drain pan

The reason I selected the Dimple brand is that the magnets
are high temperature rated and the drain plug is ferrous
metal. And the reviews on other sites are very favourable
with regard to finish quality.

The commonly available anodised aluminum drain plugs may
come in pretty colors, but the problem is that the magnets
may loose their magnetism when the oil gets hot and the
magnet may come loose since it is glued in due to the fact
that magnets have no attraction to aluminum.

THE TRUTH ABOUT MAGNETIC DRAIN PLUGS

In the automotive enthusiast world, magnetic drain plugs
are presumed to be used to remove ferrous material from
oil. That leads to a lot of arguments about efficacy.

While that will happen to some greater or lesser degree,
it turns out that engineers have a different reason for
specifying magnetic drain plugs.

An aircraft mechanic set me straight as soon as he heard
"magnetic drain plug".

He said, "oh a magnetic chip detector". Same device but
different usage.

He explained that these magnetic chip detectors are
required equipment and they are inspected at regular
intervals for ferrous material pickup as a means of
detecting possible unusual wear that might lead to
catastophic failure.

Most of them have self sealing valves that allow regular
removal without excessive oil leakage. Some of them have
dual magnets wired to warning lights such that ferrous
metals bridging them will light a warning lamp. Some of
these latter ones have "burn off" circuits to burn up the
material to extinguish the warning if the pilot feels that
it is permissible to do so.

The bottom line is that you hope to never see material in
any meaningful quantity on the magnetic drain plug. It is
there as a warning device.

This makes sense when acceptable ferrous material content
in a used oil analysis is in the under 25ppm range. That
amount is likely not detectable by the naked eye.

Once the engineering rationale for magnetic chip detectors
is understood, there really shouldn't be any controversy
in installing a magnetic drain plug.

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