there you have it, folks, straight from the denny the fraud's mouth.

denny, go back to study hall. It is not lunch time yet.

Some automotive engines use oil as light as 5W20 in 100 degree F heat and yet
go 100,000+ miles without any oil related problem. Many of todays aluminum
engines have done away with camshaft bearings and are using the lighter oils.

But the weight or viscosity is not the total picture. Much of this depends
on
oil pressure. The theroy on light oils is that it is able to flow faster and
since there is no, or very little oil pressure at start up, pressurized oil
is
able to reach component pasts faster. Since 97% of engine wear occurs at
start
up you can see where this is critical. Lighter oils also disapate heat
faster
thusly the engine runs cooler.

As long as oil pressure is maintained in order to provide sufficient flow
there
will be no discernable wear with using 30wt in an engine perscribed to use
40wt
oil. Heavy weighted oils are used primarily in engines with lower oil
pressures or in extreme operating temps. In using a lighter weight oil you
should see a small drop in pressure, but as long as the engine maintains oil
pressure specs you will be fine.

Dennis
ASE Certified Master Auto Tech
and Marine Engineer in training

OK, so I'm sitting around with the captain and his engineer friend on the
new
boat I'm project managing/co-captaining and we are trying to work out how to
run the same weight oil in the engines, gensets and trannys so we only have
to
fill the clean oil tank with one weight oil and not carry any extra buckets
of
different weight oils with us.
The CAT engines and ZF trannys can use 40W oil as per their specs but the
Northern Lights gensets only recommend up to 30W oil. The CATs could run 30W
but only at 86 deg. ambient air temps. We will certainly be seeing higher
temps
than that.
I tell the capt. and eng. that based on the ambient air temps we will be
seeing
even with the Delta-T fans that if it weren't for a warranty issue I
wouldn't
hesitate to use 40W oil in the gensets.
The capt. and eng. disagree. They start saying that running a heavier weight
oil could cause wear problems and make the engine work harder over time. And
as
an example they compare it to what can happen if you use a heavy weight oil
in
a high revving street/race car. I point out that this is a diesel not a high
revving street/race engine. They back off that point a bit but we still go
round and round in a civil fashion.
In the end we will end up putting 15-40W oil in the tank for the engines and
gensets (as per specs) and keeping some 40W in bottles for the trannys.

But other than the warranty concerns, I'm I missing something here?
Would using 40W over 30W in the gensets with of course changing it at the
proper number of hours and making sure that the ambient temps never get low
really cause any long term problems?



Capt. Bill