Dipstick Accuracy & Oil Level

[Mike Wattam <MikeWattam@domain.elided>]

Hi Daryl (and Brian)

I'm afraid the sump oil level accuracy is not that brilliant, even on cars
with aluminium sump pans.  The Stag especially seems to suffer from denting
of the oil sump (careless tyre fitters/DPO) which always reduces capacity.

The oil capacity of the Stag is in any event not great for the amount of
work it has to do in carrying away heat alone, so I would always err on the
side of keeping the oil level at the top of the dipstick - and wouldn't
worry too much if I overfilled it slightly if it is burning oil.  

On the Stag there is a good clearance to the crank webs, but if it was
overfilled so much as to hit the crank webs and you would hear the noise,
and see all the oil leaks/exhaust.

Regarding the loss of oil pressure under braking, I am not sure about the
Stag but on the Dolomite Sprint Slant 4 there is a baffle in the sump pan
to reduce the effect of oil going forward under braking, so I am hoping the
Stag is the same but somehow I doubt it as the sump is pretty deep and I
expect Triumph relied on that as being the cheaper way out.  As I am sure
has been said before the oil has a lot of work to do in the Stag, and
temporary loss of oil pressure for just a few seconds can easily send the
crank and bearings to that great scrapyard in the sky.  The oil pickup pipe
is in the back right hand side of the sump, which makes it worst braking
hard on a right hand bend.  Shades of my Mini rallying days.  It would be
very simple to add a baffle to the Stag sump pan when off the car.

It is not the lack of oil while braking itself which causes the problem,
but those first few seconds of acceleration before the bearings are fully
coated in oil again.  I had this twice on an Alfa Romeo which was similarly
hard on it's oil and for the benefit of those who reckon oil guages are
really useful, the guage only showed noticeable loss of pressure AFTER the
engine damage had been caused and the engine had started making noises  -
all within the space of a few seconds.  And certainly not what you should
be concentrating on when under heavy braking.  This happens with other
vehicles too.  Be vigilant.

Mike Wattam
Chairman - Triumph Stag Register