Thread: The oil on oil for Disco V8

Originally Posted by PhilipA

I once drove from Amman to Riyadh in one day during August in a 1981 2 door with 125K miles on it. Ambient temp was 40c early morning to 55c all day for distance of 1940Km. Oil temp was pegged and water temp was at lower end of red zone most of the day. Pressure was also way down.

Oil was Shell super 20-50 , dino oil as this was 1985. Used about 1.5 litres.

I pulled the engine down soon after as the oil pressure light was coming on. Turned out to be a gone pressure switch. Ah live and learn.
The bearings showed normal wear, the rings were carboned up but the bores were perfect.The cam was buggered but this well predated the trip.
The point I am making is that you can use just about any 20-50 on the market , and it will well lubricate a Rover V8 In the most extreme circumstances found in Australia. I also doubt whether anyone in Australia needs an oil cooler unless maybe towing in 50C..


Re Penrite. Their ONLY USP can be that they have heavier oil as a point of difference. I used to use it but I now reckon its a crock as all it does is decrease fuel economy. It also reduces oil usage but if your engine uses more than 1.5 litres in 5000Km, ie needs topping between changes , you perhaps should look at the valve guides. Why is it in Australia we think our conditions are unique in some way?? The Middle East for example has much harsher conditions with colder winters and hotter summers and the major companies' oils there are the same as sold anywhere else..
Rover recommended oils also include 20-40s if I recall correctly.
Regards Philip A

FWIW - I agree!.....with all above...esp Middle East bit AND Penrite's advertising BLEATINGS.

BTW - it's v. well known that the V8's 1st casualty is nearly always the cam wear on camshaft.....that's why you want best possible anti-friction protection, especially @ start -up......also these engines don't run at very high oil pressures - they rely on volume of oil flow between clearances.....of course I'm talking about the original [GM Buick] design V8's here not BMW 4.4 or new Ford/Jag 4.4 and 4.2SC

This is an extract from an article taken from http://theoildrop.server101.com/cgi/...;f=56;t=000022

EP lubrication is a "boundary lubrication" phenomenon in which the full fluid film is absent, and in which additives of the film-forming EP additive types chemically combine with the metal surfaces, thereby preventing welding and galling of those surfaces. Sulfur-Phosphorus, the Chlorines, ZDDP, MoTDC, and SbDTC all fall under this category.

EP lubrication for the dispersed additives involves an electrostatic attraction of the dispersed molecules to the metal surface. These materials, such as borates, calcium complexes, or molybdenum disulfide (powder) are suspended in the oil carrier and literally coat the metal surfaces after attraction.

Friction Modifiers, Extreme Pressure additives, and Anti-Wear additives are all friction modifiers to one extent or another, but anti-wear additive films do not provide protection under long-lasting or sustained pressures, due to attrition. However, they will quickly reform providing enough additive reserve was included. So at times the delineation between AW and EP additives is not always clear and somewhat arbitrary. EP films, under extreme pressure, stay intact at higher temperatures and form/reform these films rather quickly after the pressure has passed. Most EP films also form at room temperature, unlike engine oil AW or FM additives. So we can say that the major differences between AW and EP films are that EP films:
a.) Form/reform more quickly
b.) Act or get to the base metal at room temperature, i.e., does not require
elevated pressures/temperatures to start the film reaction (the exception is the phosphate esters)
c.) Act as anti-galling, anti-welding additives
d.) Act/react when the pressures or loads are above what the AW additives can handle.
e.) AW additives form plastic films which "glide," whereas EP additives form films which shear or "slide."