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Lubricants for the Porsche 928
This informative article has been written and compiled by
Doug Hillary. Just part of his extensive experience
- Automotive Engineering - Trained by BMC in NZ
and England (1957-1964) Included the first export Mini prototype's
development in 1959.
- Caltex-Chevron Copenhagen Denmark - operated a
'Quick Service Vehicle Development' Training Centre.
- Technical Trainer for the NZ Trucking Industry
- Road Transport Industry Training Board.
- Alex Harvey Fellow '75 - Heavy Vehicle
Development/Programmed Maintenance (GM, Cummins, Leyland, Daimler
Benz, Volvo - worldwide).
- Senior Executive Officer - Australian Road
Transport Industry Training Committee.
- Self employed since 1988 Road Transport &
Training Resources P/L (incl 1989).
- Management Consultancy Truck Driver training
Initial developer of 'TruckSafe' format.
- Truck Fleet Owner - Interstate Includes;
Lubricant's development with Castrol and Mobil, Risk Management with
all Insurers, Workshop & Vehicle Management.
Doug's years of experience in the 'Industry' (and ownership of his '89 S4) has given all of us in the 928
community an excellent tutorial on this often queried topic. Many
thanks Doug for taking the time and sharing your vast knowledge with us. - Leonard Zech, Webmaster.
Many thanks Doug. Had not heard the term
'Barrier Additive' before. I found this site which gives a good
thumbnail summary/addition to your info: bobistheoilguy.com
- John Cumming '89 S4
The subject of lubricants for the Porsche 928 is both complex yet
really quite simple.
Complex because of the extensive range of modern oils available - a
truly bewildering choice.
Simple because it is all written in the Porsche 928 Driverís Handbook
- and it has been from new.
A basic understanding of lubricants and the 928'e engine might help
make the complex part simple!
A 'Religion' for some!
Many people treat their automotive engine oil choice as a 'religious' issue. They have their own special brands or brews.
Or they use the brands and types recommended by so-called 'experts'. Sometimes the most likely choice circumstance is simply that
advertising played the major role.
Sadly, except at the very extremes of racing or rallying there is
actually very little difference between the various brands and types of
oils - both mineral and synthetic. As long as they meet the API and/or
ACEA standards and have Motor Manufacturerís Approvals they will perform
the same task.
Only at the extremes of racing or rallying where special 'brews' or formulations are prepared by Oil Company Chemists (and their additive package supplierís Chemists too) for specific engine
applications lubricantís may almost perform miracles. Sometimes these
oils may be prototypes of new products to come on the market later.
There are no magic oils!
No magic elixir lubricant(s) exist despite the many claims
otherwise. Yes, some oils are marginally better than others and in a
general sense you get what you pay for. Ester based Group 5 synthetic
lubricants (sometimes using coconut oil 'esters' etc. and other
more advanced substances) certainly have some benefits. They are quite
expensive and the benefits occur mainly under severe heat stress and at
temperatures below those experienced in Australia. Some synthetic oils do
minimise wear in valve train components but this only shows up after many
hundreds of thousands of kilometres of use - much longer than most people
will keep their cars in most cases.
Some synthetics do allow extended drain intervals - but Porscheís
recommended drain intervals are already long enough even with the 'normal' recommended mineral oils - so thatís not an issue for
As with most things generally however the most expensive lubricant is
most likely the better quality lubricant! Simply though it may not be the
most cost effective for you.
No 'supa-dupa' extra additive such as Slick 50 etc. will
extend the life of an engine. They may reduce oil consumption or reduce
noise - but always at a cost. No independent research has ever
conclusively proved that the likes of Teflon actually works at all in
engines. In fact DUPONT Teflonís inventor says that it doesnít despite
some manufacturers advertising to the contrary
Some sophisticated chemical additives such as ZDDP, MoS2 and MoDTC
however do work very well - at the levels already carefully blended into
many high range lubricants and hence the higher prices. With these
chemicals it is not a case of the more the better - in fact it may be the
reverse. So donít add anything to your oil - it can do more harm than
good. Some may actually pollute exhaust catalysts or cause extra deposits
on pistons, ring lands or cause oil foaming and etc.
More, and very complex chemistry is being blended into todayís
lubricants than ever before - and there is more to come. Some new built-in
components of the latest base oil formulations and additive packages are
truly amazing performers! They are needed in todayís and for tomorrowís
engines - the fuel economy, emission and technology requirements demand
their continuing development
You should not add any extra additives and spoil the Oil Chemistís
carefully structured brew.
As examples and for your interest I use the following lubricants in my
1989 928S4 Auto:
Engine - Mobilís Delvac 1 5w-40 CI-4/SL - a HDEO mixed fleet fully
synthetic diesel oil.
I do a UOA every six months and the OCI is annually or at 20k - earlier
if the UOA determines this
Auto Transmission & PAS - Castrol Transmax Z synthetic Dexron 3
(a "lifetime" fill - 300 000kms or three years)
Diff - Castrol Syntrax 75w-90 synthetic GL5 gear oil
(a "lifetime" fill - 300 000kms or three years)
If my car was a manual 928 then Castrol Syntrax 75w-90 would be in the
Doug Hillary '89 S4
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