A CAUTIONARY NOTE - THIS DOCUMENT WAS PREPARED IN 2002 AND IS NOW (03/2008) OUTDATED - INTENDED TO BE USED AS AN HISTORIC REFERENCE POINT ONLY

Lubricants for the Porsche 928, 928S, 928S4, GT and GTS

The subject of lubricants for the Porsche 928 is both complex yet 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 Driver’s Handbook - and it has been from new

Many people treat their automotive 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". Or and sometimes most likely, advertising palys a major role. Sadly, except at the very extremes of racing or rallying where special "brews" or formulations are used there ...

The following data was collected and tabulated from a Rennlist thread in 2007. "Hot" means after about 30 minutes of engine on time. The factory states for oil to be at or above 80C. It appears that Porsche expected the 928's OP to be "around" 1.5bar at a hot idle and (to all intents) 5bar at 4000 rpm (some at 5000rpm). Porsche's minimum expectation is to get the engine's speed reading of 5bar. The 928s OP gauge is notoriously "inaccurate" but it is a reasonable OP "indicator"

(Overrides and/or supercedes all MY Driver Handbook recommendations)

Multigrade (mineral/synthetic) lubricants

10w-30 MY> 92 (synthetic)

5w-40 MY> 93,94,95 (synthetic)

10w-40 MY> 84,85,86,87 mineral or synthetic

10w-50 MY> 84,85,86,87 mineral or synthetic

15w-50 MY> 78>81,82,83,84 mineral or synthetic

20w-50 MY> 78>81,82,83,84,85,86,87 mineral or synthetic

Monograde (single viscosity grade) Heavy Duty (petrol/diesel rated) mineral lubricants

SAE20 MY> 78>81,82,83 and then from 89,90,91

SAE30 MY> 78>81,82,83 and then from 89,90,91

Note 1 - All MYs to 1988 - 20w-50 viscosity is not to be used below -15C

Note 2 - All MYs from 1988 - only use lubricants from the Porsche Ap ...

 On Mon, 2008-03-10 at 08:47 +0000, buchananautomotive wrote:

> ZDDP and moly , but I must admit I am not a big fan of the much
> larger amounts of detergent in the diesel oils for the use in petrol
> engines ( I am just not at ease with that bit )( I am a bit fussy ).
>  Regards. BB.

This paper on ZDDP, based on research conducted by N.J. Mosey, T.K. Woo,
et al, at the Universities of Western Ontario and Ottawa (which was
brought to the attention of the list by Bruce B), states on ...