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----- Original Message -----
From: "Richard Notton" <Richard@fv623.demon.co.uk>
To: "Military Vehicles List" <mil-veh@uller.skylee.com>
Sent: Monday, May 15, 2000 10:31 AM
Subject: Re: [MV] Ferret fluid and Catch 22
>
> ----- Original Message -----
> From: "Jim Gilmore" <jgilmore@oeonline.com>
> To: "Military Vehicles List" <mil-veh@uller.skylee.com>
> Sent: Monday, May 15, 2000 7:33 AM
> Subject: Re: [MV] Ferret fluid and Catch 22
>
>
Good Morning,
Just a small update on the OM 13 hiatus. I called the tech labs at Fuchs
Lubricants refinery yesterday.
Silkolene (Fuchs brand name) 779 = Aeroshell Fluid # 1 = OM 13. These are
all aircraft hydraulic oils of ISO 15 grade but tweaked with Viscosity Index
(VI) improvers to allow operation to -60 degrees Celsius. Being the stuff
that keeps 400 people safe at over 30,000 ft while it unobtrusively goes
about its business of moving or not, as the case might be, the wiggly bits
of a 747, it is furnished with every nicety you could imagine plus a
guaranteed cleanliness straight from the can that doubtless well exceeds
COMPAR 2.
A nominal 0.001% (max) stearic acid is added as a flow improver largely for
the VI enhancement, now this is not much. Being metric we get 25 litre
drums as the equivalent to the old 5 imperial gallons, this addition is
really small. Typically the price of 779 is some 8 times that of commercial
ISO 15 like Silkolene Renolin 15, the commercially standard and very widely
used ISO 32 oil does have some extra tweaks to give extended low temp
operation, certainly below that even seen in the US and heaps lower than
you'd like to take your Ferret out in.
Torque converters especially are very tolerant of viscosity changes, the
clever bits in the hydraulic oils are for pump protection and operation, the
receiving end of the hydraulic grunt so generated largely couldn't care
less.
On the subject of engine oil ash generation and the danger of high rate
piston ring wear using chemically altered multigrades in intended high oil
consumption engines (which the RR B Range most certainly is, DDA two-cycles
also) they advise that the industry has now chosen to hydro-crack the base
stock thus forming more long-chain hydro-carbons and so alleviating the need
for excessive additives to afford multigrade characteristics. The
suggestion is that medium detergency engine lube oils are now very different
things from the early and ash aggressive examples, these changes have also
been made to meet the EU regs on truck lube oil pollution now in force here.
Fuchs suggest one of the Silkolene "Perma Visco" engine oils would be highly
suitable, likely 10/40 in temperate climates.
Whilst the Ferret, Saracen, Saladin, Stalwart is reasonably well known in
the US, you may not have encountered the other GS trucks of that era, all of
these require SAE 30 in the gearbox be it conventional or a pre-selector
type. In agreement with all the other company advice, Fuchs advise against
any multigrade here since the shear stability is exceeded, after a short
time these gearboxes will convert a multigrade back to its base stock,
typically SAE 20 for a 10/40.
This produces a slight dilemma and is peculiar to each MV owner with old
Brit ironware and whatever else they might have tucked away in the garage.
Stock up on a modern medium detergent multigrade for the engines and keep a
smaller stock of SAE 30 MIL 2104 B, C, or D for the gearboxes, or just have
loads of 30 on its own.
Personally I will have to see what price advantage there might be, the Fuchs
tech man said the typical out-of-season winter lay-up with occasional cold
oil runs, as we have discussed before, is far more dangerous with
condensation/combustion acid hassles than the ash consideration and so
advises a change at the end of one, and beginning of the next show season.
The one thing that doesn't leak on my 623 is the gearbox so a 10 (imp)
gallon oil change per annum may well be less costly using a very common,
high demand, diesel 10/40 rather than the fairly cheap, but to order, MIL
2104 SAE 30.
Richard
Southampton - England
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