On Dec 7, 10:55*am, "Doctor Drivel" wrote:
"js.b1" wrote in message
Actually since about 2004 Mobil 1 is no longer a true fully synthetic.

So there is no difference between Magnatec and Mobil 1?

Yes, but they are both "synthetic and not synthetic" :-)

Does Magnatec actual stick to the
metal bearings because of magnetism?

It is polar attraction.

What I do not like about Magnatec is 1) its ash figures 2) its ability
to completely **** off hydraulic lifters that are otherwise silent 3)
its tendency to gloop out of the pan which I found disturbing.

The problem at startup is how quick you can get pressure to the
bearings, before then you rely on the additive package. Synthetic
flows better at low temps (and in Canada some engines go bang with
poor oil, others have a temp sensor which will restrict max rpm).

What has milage to do with it?

Low annual mileage is often lots of short trips.
Lots of short trips means the engine spends most of its time running
in O2 sensor open loop mode, rather than closed loop. That is because
the ECU is dumping more fuel in to 1) get the engine warmed up and 2)
get the cat up to temperature. This tends to increase fuel dilution of
oil, fuel washing of cylinders, increase water concentration in oil
since it does not get hot enough (coolant gets hot fast, oil takes way
longer hence coolant-to-oil heat exchangers above oil filters which
use the hot coolant to heat the oil during warmup & vice-versa when
the engine is hot).

Low mileage short trips are considered "adverse duty", there used to
be two oil change specs in the manual - one for long distance driving
and a much shorter one (50%) for adverse duty. So a 9,000 mile oil
change interval could be 4,500 miles in stop-start winter driving
where the engine never warms up.

The classic killer of old engines used to be sludge - lots of short
trips such as 5-7 miles to work. With longer commutes this problem has
reduced, but it can kill modern diesels with diesel particulate
filters. They fail to regenerate sufficiently, the oil cokes up, and
suddenly the oil pickup screen is stuffed, turbo or rod goes and the
bonkers expensive engine is toast.