More often than not fuel in the sump oil when a mechanical pump is fitted=
is indeed a split diaphragm in the pump.
<<There have been some debate about using modern multi-grade oils in WWII=
engines.>>
We have been round this before but the findings from here after asking th=
e
technical departments of several multi-national oil companies, and
Rolls-Royce, are worth re-posting. The answers were virtually identical
from all sources.
Current multi-grades are so detergent that deposits will be rapidly remov=
ed
and blocked oil filters and/or (paradoxically) fine oil-ways could rapidl=
y
result. The available apparent equivalents to SAE 30, eg., 15/40, 20/30,=
30/30 etc., are more fluid and can result in low operating pressure.
Multigrades are not as strong as straight oils and in the case of pressur=
e
fed gearboxes with their own pump and supply, originally specified for a
straight engine oil, the use of a multigrade is highly unadvisable.
The WWII engines (and later) were necessarily designed with larger
tolerances than today owing to the materials and technology of the day
together with the envisaged severe duty, oil consumption was intentional =
to
ensure reliability. The modern multigrade apparently burns to a fine but=
very abrasive ash that can rapidly wear piston rings, especially the top
ring and its land. =
(To this day it seems pertinent that Detroit Diesels devote several pages=
of their manual to oils, specifying SAE 30 only, as multigrades are
unacceptable)
For operation in permanently low temperatures either electric heaters wer=
e
employed or the oil grade was changed, eg., RR specified SAE 30 to -5C
(23F) and SAE 10 for -5C to -15C (23F to 5F).
Although not necessarily a stock item on the garage forecourt, it seems
that straight oils are readily available in 25L/5gal drums from a good
distributor and meet the ubiquitous MIL-L-2104 spec. These quantities ca=
n
be advantageous on price and convenience as the subject vehicles usually
hold a fair quantity and need a frequent top-up.
Hope this helps.
Richard
(Southampton UK)
===
To unsubscribe from the mil-veh mailing list, send the single word
UNSUBSCRIBE in the body of a message to <mil-veh-request@skylee.com>.