40W oil causing wear problems over 30w?
 

Rich, viscosity of the oils in question is a function of their temps. The
definition of 40W is 40W -- at the given operating temperture. That is to say,
that given the definition of the standards for oil, 10W-40 has the same lube
properties -- at engine cranckcase operating temp -- as 40W. This is "close
enough" to be true that it is accepted by the industry as a standard.

That said, transmission oil typically operates at a lower temp than engine oil.
That means that under normal operating conditions 40W **as used in a
transmission** is more viscous than 10W-40.

I would be inclined to use 40W in a tranny unless no 40W is available when the
tranny needs oil, but 10W-40 is.

For the transmission application I'd opt to use the EXACT grade, as the
viscosity in this case relates to the "film strength" needed to keep
metal-to-metal contact to an absolutel minimum. If you used other than
whats specified you are vulnerable to scoring, galling and .....
ability to reduce wear of the gear tooth surfaces. A transmission or
gear set is considered an "extreme pressure" (lubrication-wise)
application and the oil viscosity (as specified) is VERY important to
keep metal to metal contact from ocurring... in this case the oil
supports the load between the gears and prevents metal to metal contact
.... only if its the specified viscosity. . In a transmission the
reduction in wear is a function of the exact lubricity specified. If
the trans. mfg. specifies 40W (Not 10-40W), then USE 40W .... only.

For the engine applications, the viscosity enables the bearings
(journal - crankshaft) to be lifted to the proper height within their
journals, so that the oil supports the shaft precisely at dead center
in the journal so that the shafting is in the exact cente r.... and has
equal and equidistant clearance (at the higher range of engine load) by
the pressure generated in the gallery/pump and somewhat by the
viscosity. Why viscosity is important is that viscosity (resistance to
flow) will help to support the piston load during the combustion
stroke. ........ However, If you are not 'lugging' the engine (low
rpm at HIGH load) then using a viscosity index of 1 grade lower than
specified ..... should NOT be a problem. If however youre running WOT
(wide-open-throttle) and high load ... then it becomes important to
match the specified viscosity grade (and operate at the specified
engine temp. ... as set by the thermostat.).
The short answer: OK to run lower viscosity, just watch the oil
pressure to be sure its 'similar' as when running the 'specified'
viscosity index oil.

In article , 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

40W oil causing wear problems over 30w?
 

Nope - common misconception!
When you're engineering a gear set, you need to select the correct film
strength so that the clearances BETWEEN the epicyclic surfaces do not
come in contact. A gear set typically is an unpressurized application.
The more power being transmitted the higher the film strengh needed -
and there is a correlation of (kinematic) viscosity (viscous shear) and
what it will support in load without "squeezing out" and permitting
metal to metal contact. ...... totally unlike a pressurized
application like a hydrodynamic bearing journal, although the
mathematics is the same.

40W oil causing wear problems over 30w?
 

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

40W oil causing wear problems over 30w?
 

On Mon, 14 Jun 2004 10:20:51 -0300, Earl Haase
wrote:
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.

====================================

Presumably the genset needs a lot less oil as well, and the waste oil
can all go in the same bucket.

40W oil causing wear problems over 30w?
 

Rich, SAE standards for 10W-40 oil call for the same film strength at engine
operating temps as 40W oil.

To be sure, some will argue whether the standards are accurate or not (there is
room to argue).

That said, I too would use 40W in a transmission over 10W-40 unless I ran out
of 40W. A transmission runs cooler than an engine and is oil bathed so has no
issues with lack of lubrication upon startup.

Nope - common misconception!
When you're engineering a gear set, you need to select the correct film
strength so that the clearances BETWEEN the epicyclic surfaces do not
come in contact. A gear set typically is an unpressurized application.
The more power being transmitted the higher the film strengh needed -
and there is a correlation of (kinematic) viscosity (viscous shear) and
what it will support in load without "squeezing out" and permitting
metal to metal contact. ...... totally unlike a pressurized
application like a hydrodynamic bearing journal, although the
mathematics is the same.

40W oil causing wear problems over 30w?
 

As far as prelubing the engine before start up goes, do you
really care that much?

I do. Race mechanics do. Aircraft mechanics do. The US Navy does.

Listen to an engine upon startup with heavy oil in it (even at summertime
temps) and hear all the grinding and banging and clattering going on inside the
engine for the first ten or fifteen seconds, let the engine warm up a couple of
minutes, shut it off, restart and listen again.

If you can't hear the difference, replace the battery in the hearing aid.

40W oil causing wear problems over 30w?
 

Not being a fan of multi weights I

the designers of engines are very much in favor. the builders of engines are
very much in favor. the mechanics who work on engines are very much in favor.
The users who get long life from engines are very much in favor.

40W oil causing wear problems over 30w?
 

"JAXAshby" wrote
Listen to an engine upon startup with heavy oil in it (even at summertime
temps) and hear all the grinding and banging and clattering going on
inside the
engine for the first ten or fifteen seconds, let the engine warm up a
couple of
minutes, shut it off, restart and listen again.

If you can't hear the difference, replace the battery in the hearing aid.

JAX is right.

Some 'Shovel Head' H-D owners had to redo their top ends every season,
sometimes more often up north. Turned out the problem was that "everybody"
knew that heavier oil was best and some even used 70 wt. Had to to get the
oil pressure in their roller-bearing Hogs up to that found in a plain
bearing Chevy! Of course it took an hour to get oil up the tiny tubes
feeding the valve rockers - oil which incidentally helped cool the head and
valves. H-D spent mucho $$ developing a multigrade to solve the problem but
"everybody" knew they didn't give enough oil pressure. Minnesota boy I know
rebuilt 7 times in 5 years then went to H-Ds multigrade and last I heard
hadn't had to rebuild in 10 year.

The only problem with using multigrade oils in some older engines is their
detergent capabilities. With few exceptions they are designed to trap and
hold dirt til it can be removed by our wonderful full-flow filters. That's
one of the reasons motors are lasting 200,000 and more miles longer than
they did in the '50s. But what if your or BSA or Triumph or Atomic-4 don't
have a full flow filter? Well then get nondetergent multigrades from Morris
in England.

40W oil causing wear problems over 30w?
 

JAXAshby wrote:

I do. Race mechanics do. Aircraft mechanics do. The US Navy does.

The only thing you've ever prelubed is your Speedo, Jax.

Tell us all about those airplane engines that get prelubed before
starting ... care to name a couple? Rhetorical question of course, Jax
has never answered a single question in response to one of his fantasy
statements.

Rick

40W oil causing wear problems over 30w?
 

Rick -- for some reason, I suspect that by "Speedo," you aren't referring to
a speedometer. lol

--
Karin Conover-Lewis
Fair and Balanced since 1959
klc dot lewis at centurytel dot net


"Rick" wrote in message
nk.net...
JAXAshby wrote:

I do. Race mechanics do. Aircraft mechanics do. The US Navy does.

The only thing you've ever prelubed is your Speedo, Jax.

Tell us all about those airplane engines that get prelubed before
starting ... care to name a couple? Rhetorical question of course, Jax
has never answered a single question in response to one of his fantasy
statements.

Rick