I'll let you into a clue. Blend Mobil one for Saab and stick it in a
Saab bottle, it's Saab oil. When your lord and masters cut corners,
stick Castrol Magnatec, or YoMamma smokey burn in the Same Saab oil
bottle, it is Saab oil.

I did read on one of the OC magazine, that Saab through GM had done a
deal with an oil company I had never heard of, to produce one oil for
all Saabs, from the Turbo Diesels, to the LPT, to the HOT AERO models.
And it had a longer life cycle. Now what was it about Saabs, Toyotas etc
on Synthetic in the states, with longer service interval suffering from
sludging.

Below is an article written by John Rowland, Silkolene/Fuchs Chief R & D
Chemist for 40 years.

Quote:

Costs of synthetics vary considerably. The most expensive are the
?Ester? types originally only used in jet engines. These cost 6 to 10
times more than high quality mineral oils. The cheapest synthetics are
not really synthetic at all, from a chemists point of view. These are in
fact specially refined light viscosity mineral oils known as
?hydrocracked?. These have some advantages over equivalent mineral oils,
particularly in lower viscosity motor oils such as 5w-30 or other oils
with a low ?W? rating such as 5w-50 etc and they cost about 1.5 times
more than good quality mineral fractions. We use several different
grades of this base oil, where appropriate. This is the ?synthetic?
which is always used in cheap oils that are labelled ?synthetic?. Yes
it?s a cruel world, you get what you pay for!

Now, you may ask, why are these special mineral oils called ?synthetic??
Well, it was all sorted in a legal battle that took place in the USA
about ten years ago. Sound reasons (including evidence from a Nobel
Prize winning chemist) were disregarded and the final ruling was that
certain mineral bases that had undergone extra chemical treatments could
be called ?synthetic?. Needless to say, the marketing executives wet
their knickers with pure delight! They realised that this meant, and
still does, that the critical buzz-word ?synthetic? could be printed on
a can of cheap oil provided that the contents included a few percent of
?hydrocracked? mineral oil, at a cost of quite literally a few pence.

So, the chemistry of ?synthetics? is complex and so is the politics!

The economics are very simple. If you like the look of a smart well-
marketed can with ?synthetic? printed on it, fair enough, it will not
cost you a lot; and now you know why this is the case. But, if you drive
a high performance car, and you intend to keep it for several years, and
maybe do the odd ?track day?, then you need a genuine Ester/PAO (Poly
Alpha Olefin) synthetic oil, such as PRO S or PRO R. This oil costs more
money to buy, because it costs us a lot of money to make, very simply,
you always get what you pay for!

UNQUOTE:

Here is a link to some specs of oils.
http://www.opieoils.co.uk/lubricants.htm

And Biased toward AMSoil but,
http://www.bestsyntheticoil.com/amsoil/index.shtml#mobil2
"Nothing Outperforms Mobil 1? Wrong!!
Just compare the technical specifications. We've got the data on the new
Mobil 1 SuperSyn 5w30 and we've compared it to AMSOIL 5w30. Guess who
comes out on top in every category? You guessed it ... AMSOIL!

According to the ASTM D4172 Four Ball Wear Test, Mobil 1 SuperSyn 5w30
allows 50% more wear than AMSOIL 5w30. 50%! What about NOACK volatility
(the measure of an oil's rate of consumption under high heat/stress
conditions)? Mobil 1 consumes at a rate nearly double that of AMSOIL.
And how about TBN (Total Base Number - the measure of an oil's ability
to neutralize acid build-up and corrosion)? AMSOIL has a TBN value
nearly 50% higher than Mobil 1.

Of course, there are other areas where AMSOIL comes out on top as well
such as a viscosity index score that is 12 points higher than the Mobil
1 product which isn't even on the charts (we didn't want to beat up on
them too badly). Why don't you take a look at the charts for yourself?
"

And this link goes into quite a lot of detail over both Syntec, and
Mobil 1 and the PAO Synthetic/Cracked petroleum synthetic debate too.
http://www.clubwrx.net/forums/archive/index.php/t-4702.html

I get Millers off the shelf at the local autfactors I use.
Another has Valvolene in 5 litre and trade sized drums.

Mechanic I used once or twice uses Millers full synth, in everything
from Micras to Diesel 4x4s. he bulk orders it and gets it delivered by
tanker. Normaly gets the last drop of the day, so gets what left above
his order for the price of a couple of pints to the driver.

Redline, Valvolene, Silkolene and Millers can be mailordered from
DemonTweeks in Wrexham, or bought over the counter if you are passing.

I actually haven't seen Silkolene in any shops. Seems to be Castrol,
Carlube or Homebrand almost everywhere.

Start using synth-oil, and keep an eye on the colour of the oil. It's okay
for it to turn dark brown, but does it go too black, change oil and filter.
This means that the oil is "cleaning" out old deposits.