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-----Original Message-----
From: mblair1@home.net <mblair1@home.net>
To: Military Vehicles List <mil-veh@uller.skylee.com>
Date: 15 April 2000 19:00
Subject: Re: [MV] Oil changes
>
>DaveCole <davidcole@tk7.net> wrote:
>> Regarding oils and old LOs. I think that everyone needs to remember
>> that the 30W oil of long ago is pretty much non-existent now. Even
>> the 30W non detergent stuff you can buy is of a much different
>> quality than the oil of WWII.
>
>One small point: I don't dispute that oils have changed a lot since
>WW-II, and that this is of particular concern to those of us with MVs
>of not-very-recent vintage (that would be most of us, I guess).
>However, the specific deuce and HMMWV LOs I cited are dated 1983 and
>1990, respectively. Is today's SAE 30 much different from the SAE 30
>of 10 years ago?
>
Around 1950 MIL-L-2104B was the standard engine lube, today it is 2104D, asking
the oils man at our Defence Equipment Research Agency I'm told the difference is
mainly in detergency with minor improvements in performance elsewhere.
In respect of climatic range the engine specs seem to allow SAE 30 over a very
wide band but I am looking at the one common application RR gas engine that
powered everything from "jeeps" to tracked SPGs in one variant or the other.
The design was based on a 1930s engine and tested late in W.W.II by trial
installation in various things with full production in the 50s to equip the mil
here with a complete range of new design vehicles.
There seems to be an understandable design difference between specific mil
designed engines and domestic types, in this instance looking at the RR B Range
it follows simple basic techniques with generous allowances for longevity that
are likely engineered to the minimum in domestic types, after all the mil (the
captive audience tax-payer therefore) is paying so generally cost is no object.
At the time the mil wanted batch proving that the engines would operate at full
rated power and revs for 7 days and nights continuously on a test bed, a test
which I think would be death to a domestic design.
The quoted 23ºF - 89ºF ambient operating spec (Engine Manual TSD 702 - April
1958) may largely be a function of the generosity and modest power of the design
therefore, and installed these engines are invariably provided with an oil
cooler or some such arrangement of remote tank to provide cooling.
Relying on RR to design suitable bearing retention to alleviate any possibility
of spinning, the mil here went to 24 V systems throughout with huge starters and
a pair of 100AH batteries in everything, likely after the experience of marginal
6V systems of W.W.II, for good measure they are fitted with Ki-Gas injection
also.
>Regarding the comments that 15W-40 is being used by the Army now:
>
This is the now preferred UK mil engine oil and is called OMD80X, however it is
noted that the vast mass of UK MVs in service now are little modified domestic
types invariably powered with a turbo diesel; counting the Bedford 3 tonners and
Land Rovers you likely cover 99% of the inventory, likely the twin turbo 1200HP
RR V12 diesel that shoves Challenger along uses the same stuff.
The mil here spends ages qualifying logistic stuff like spares supply and oils,
then resists change and over-orders grossly, much to our benefit later. . . . .
. . . . . . . .
>Folks, I'm not trying to have a "my oil's better than yours" war
>here... I'm just trying to separate fact from fiction, and common use
>from correct use.
>
Me too, but in the absence of any hard evidence and totally without the
wherewithal to do my own proving or analysis, I'll stick to what the book and
manufacturer says.
Richard
(Southampton - England)
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