The *whys* of my oil pressure.new thread...

[Steady Eddie]

My Chassis is most like a W-20 WCC.
When it was built, Chevy had but one transmission "available" that would handle
32,000#--the Allison AT542..it is commonly known
as a "garbage truck" Allison, with 4-speeds forward and one really low reverse. No OD.

The P12's engine, compared to
an 8.1, it is like the 8.1 in many areas.
Brazel's recently created an Ultrapower Upgrade
for one and it tested out 258 RWHP.

To move the weight of a two-slide Newmar it is
equipped with a 4.78 to 1 rear axle ratio. My
transmissions' high gear (4th.) is exactly the
same as a 5 or 6 speed Allison's 4th. gear ratio--one
to one, direct, so it is VERY busy going down the highway, by design. Peak OE torque comes in at
3200 RPMs and running at 3K RPMs equals 60 MPH.
Exactly like running a W-20 along in 4th. gear.

So I NEED oil pressure, as much as I can get to
protect it at high torque levels. As stated, I
feel that the 5W-30 wt. oil is too thin for proper cushioning at a constant max power output. The 5W-30 looks good for the CAFE regulations that GM is trying to meet. 10W-30
is a GM "optional" oil wt. for my L21 Vortec
454. Because of its' 64K (now) mileage and me
not knowing what brand or wt. oil was in it,
I chose Mobil 1 15W-50 Syn Oil and have 70 PSI+
at road speed (3000 RPMs) and 40+ PSI at hot idle...

[Steady Eddie]

My Chassis is most like a W-20 WCC.
When it was built, Chevy had but one transmission "available" that would handle
32,000#--the Allison AT542..it is commonly known
as a "garbage truck" Allison, with 4-speeds forward and one really low reverse. No OD.

The P12's engine, compared to
an 8.1, it is like the 8.1 in many areas.
Brazel's recently created an Ultrapower Upgrade
for one and it tested out 258 RWHP.

To move the weight of a two-slide Newmar it is
equipped with a 4.78 to 1 rear axle ratio. My
transmissions' high gear (4th.) is exactly the
same as a 5 or 6 speed Allison's 4th. gear ratio--one
to one, direct, so it is VERY busy going down the highway, by design. Peak OE torque comes in at
3200 RPMs and running at 3K RPMs equals 60 MPH.
Exactly like running a W-20 along in 4th. gear.

So I NEED oil pressure, as much as I can get to
protect it at high torque levels. As stated, I
feel that the 5W-30 wt. oil is too thin for proper cushioning at a constant max power output. The 5W-30 looks good for the CAFE regulations that GM is trying to meet. 10W-30
is a GM "optional" oil wt. for my L21 Vortec
454. Because of its' 64K (now) mileage and me
not knowing what brand or wt. oil was in it,
I chose Mobil 1 15W-50 Syn Oil and have 70 PSI+
at road speed (3000 RPMs) and 40+ PSI at hot idle...

[Brazels RV Performance]

Eddie,

That coach I told you about has a Gear vendors installed on it.That would drop your RPM's by 22% & also give you the ability to split gear's on switched back mountain roads & keep your engine in the torque band.

Just a thought

[Steady Eddie]

Mike---
Good to see you here...I remember. I went out to
the GV site and could not find an app or Part #
listed. Must be obsolete or no longer made.
Do you still have the ECU/PCM P12 Part #.?

[Brazels RV Performance]

Eddie,

The Gear vendor is a Dodge pickup midship mount unit.I have an ECM here I can reprogram it with UltraPower & ship it to you.

[Steady Eddie]

Mike--

Thank you for your very kind offer. But, alas,
I am tapped out money-wise at this time. We
just got back from a 3000-mile round trip to
the NASCAR Races at Phoenix International
Raceway, and spent five-grand on our trip...
Momma is now saving/buying for Christmas, I get nothing
for the Coach...bummer...keep me in mind though.
We hosted DW's Aunt and Uncle, at the track, in
our Newmar and had a great time. Go Kevin, #29..

[speed racer]

Keep in mind that 15/40 oil may increase oil pres.but does not increase lubricating ability. 10/w30 is recomended for temps above 0. The bearing clearance dictates the oil viscosity needed. 15/40 oil will not flow properly in an engine desined for 10/30. The result is sludge build up and bearing damage.

[Steady Eddie]

speed racer wrote:
"...Keep in mind that 15/40 oil may increase oil pres.but does not increase lubricating ability. 10/w30 is recomended for temps above 0..."

Mobil 1's Web-site says that the 15W part of the 15W-50 protects and flows down to 4* above zero. Considering that I live in an area that seldom gets below 20* F.---it should be fine.

And..

"..The bearing clearance dictates the oil viscosity needed..."

I agree 100%. But without dropping the pan,
and Plastigage-ing the bearings, buying used,
how do I know what the clearances are? I have to "a$$ume" (there's that word again) that because I have had to replace the Ally once, that the rig was rode hard and put away wet.

And..

"..15/40 oil will not flow properly in an engine desined for 10/30..."

Mobil assures that the 15W-50 will flow fine.
It is made for severe service and I cannot think of anymore severe service than lugging
around ELEVEN tons of dead weight.

And..

"..The result is sludge build up and bearing damage.."

Your warning is well taken. When I made the changeover to Syn Oil I did it right. I used
a crankcase full of 10W-30 semi-syn oil as a
flush out. It came out coal black. Then, I put in the Mobil 1, also 10W-30. I drained it as I
always do, at 3K miles. It, too, came out coal black. I have done this now 3 times, and with
each drain-out, the additive package in the Mobil 1 is cleaning the internals of the Vortec.
There goes your sludge. I am careful to watch for ANY leaks from this cleaning action and have
found none. The engine is bone dry and dusty dirty. This last oil change was over to the 15W-50. And, in 93* F. ambient heat, towing a 4K# Jeep GCL, it ran cool, quiet, and strong...all you can hear is the 145-amp alternator clicking a bit. It is quite remarkable....

[Photog]

Eddie,

I am a former old time big block engine owner and I understand your concerns about 5w30 oil. When I first saw the recommendation, I thought it must be a mistake. I spoke with the folks at WH, as well as a local Chevy dealer and was told the old days of 15w50 are long gone. They claim 5w30 if fine. So I said - "When in Rome do as the Romans do". I have used 5w30 from the get go.

I live in So Cal and have spent many days running my coach in 100 to 110+ heat. Several days at 120 all day.

I have twice driven (in 90 to 100+ heat while towing at near GVW) the pass in Panamint range where Bruceh lost his engine, without even a hiccup.

IMHO, some times it seems to me that we get wound up in believing our old school ways, when there is a new school out there that really works.

Bill

[JimElliott]

Steady Eddie
I tried the M1 15-50 in my low milage (31000) 454 and the idle was a dab "ruff" due to the lifters had a slight pump up.

Changed back to "Royal purple" 15-40 which is normally run and everything is smooth again BUT it took a 50 mile drive to get it right......

I use M-1 10-30 on my toad (Saturn SC2) and M-1 is indeed a fine oil, Price was the reason for the oil change test but now through "Summit" I can buy the Royal purple by the gallon.

Hot idle oil pressure is 47 PSI and at 3000 RPM the hot oil runs 55 PSI with a digital gauge connected to the block oil plug.

Jim

[Steady Eddie]

We have to be careful here and compare apples
to apples...the 454 Vortec that I have is a
"Gen 6 and 1/2" The 8.1L in the WCC is a near
completely different animal and it even has a
different firing order, as well as a different
oiling system. That said, I still believe in oil
"body". The Mobil 1 15W-50 wt. has body. The
5W-30 cold-pours like 3-in-1 sewing machine oil,
and it doesn't seem to be any thicker at running
temperature. Using the 5W-30, I'd still be scared to death of running my
admittedly used (up) 454 out across
the Mojave in 120* weather...I think I'd park it
first, sit back and have an adult beverage and then run across at night...

[speed racer]

The 15/50 oil will probably be just fine for your aplication but not for all. I am a retired auto/truck mech./drag racer. many years ago we ran 30w oil in our cars & 60w in our race cars. As engineering improved and the need for better fuel milage they started building engines with closer clearance on bearings pistons & rings because lighter oil is easier to pump thru the engine. s a result better milage & horsepower. Today there are some manufactures recomending 0/20 oil for that resone. todays pro/stock drag racers run 0/w oil & geting 1500hp @ 8000rpm is what i call severe duty. Look to the future but don't forget the past!