Wow! That sure generated a lot of talk here. I read your post and my
understanding is that your question was, would using 40 wt instead of 30
wt cause unreasonable wear to your genset engine. The answer is no. 30
wt and 40 wt are not that much different. Once hot they will both do
the same job. A quick search on the web will show that both have pour
weights in the 20s (deg F) so start up lubrication will not be that much
different. As far as prelubing the engine before start up goes, do you
really care that much? Are you really going to do that faithfully? So
long as you don't sit there revving the engine before the oil pressure
comes up the gen engine should last for years.

However, my guess is that the real issue here is making sure you don't
bust your warranties. So if it matters that much write the generator
company and get them to give you written authorization to use the 40 wt
oil in the gen set. (My first choice.) You might want to leave out
that you've already bought the unit. It just seems that once people
have your money they tend to be less helpful. Just tell them your
interested and want to know if their units can use 40 wt oil since
you're going places where they don't have a Pep Boys on every corner.

My second choice would be if worse comes to worse, how much oil do you
need for the gen set anyway? And how many hours are you going to run it
compared to the mains? Not being a fan of multi weights I would suggest
that if you don't want to run 40 wt in the gen run it in the mains and
the trannys and keep a stash of 30 wt for the generator instead of the
other way around. You can live without the gen set but it's a long walk
home without the mains.

Earl


LaBomba182 wrote:

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