40 psi oil pressure in 454 with gtx 10w30 ?

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A few weeks ago i asked about oil for a rebuilt 454 motorhome engine.

A few days ago i found 3 quarts of 10w30 gtx hidden in the waste hose compartment.

I called my friend and asked him if he was was running 10w30 or 1540 in the rv and he said ( the white bottles of castrol )

So when we drove the rv home, it was 117°f and 1.5 quarts low. After the hour long stop n go drive, the oil psi ( 1983 dummy dash guage ) was roughly 40 psi.

Cold, its 55/60.(cold latley has been 100°f @ midnight )

Should i stay with the 10w30? Or refill with 15w40 next service?
 
I think the rv idles @ 800 rpm... So 50+psi idle cold. 35+psi hot
 
It likely has a high pressure and/or high volume oil pump.

Is it a flat tappet engine? If so I would DEFINITELY run Rotella 15w40.

Run Rotella 15w40 anyways for the next oil change and see how it performs.
 
Judging from Virgin Oil analyses I see posed here, Castrol GTX isn't what it used to be.

I'd definitely stick with a good HDEO 15W-40 for that engine as usage. The 454 in my 1995 K3500 has 272,000 miles and has always been run on the cheapest 15W-40 I could find.
 
I just figured a good syn 10w30 would free the motor up more.

I keep hearing/ reading horror stories about the cam wearing out due to heavy oil and the splash fed systems
 
OK, do we have any idea how old that GTX is ... Not because I'm worried it will go bad, but trying to get a handle on the add pak. If it's a few years old, it'll be fine until the next change.

35 psi hot idle is fine for that truck motor. As long as it comes up some when you rev it, it's all good. They need lots of oil, not lots of pressure. So HV pump is likely and if it'll make 50 psi going down the road, it's fine
smile.gif
 
Originally Posted By: Chris142
Why did you drive it with only 3.5 qts in it?


Just to be accurate... that engine holds at least 6 qts., probably more considering the application.

"Flat tappet" isn't synonymous with Rotella or 15w40. If most all its running is going to be in warm or downright hot weather it certainly won't hurt it, but if you have 40 PSI hot idle oil pressure on 10w30 I'd bump up to a beefier 10w30 before I defaulted to 15w40. I moved from Schaeffer's 7000 15w40 to 10w30 in my '85 C3500 (flat tappet 454) a year and a half ago and that engine seems very happy with the change. You need all the power and as little parasitic drag as possible in that application, so if a stout 10w30 is more than adequate why waste the power of pumping a 15w40?
 
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Originally Posted By: Chris142
Why did you drive it with only 3.5 qts in it?


5.5 quarts.

7qt system
 
The gtx is maybe 2 years old. the rv sat for 1 year. Friend changed it and took it camping 2 times before he parked it.
 
Originally Posted By: Alex_V
You need all the power and as little parasitic drag as possible in that application, so if a stout 10w30 is more than adequate why waste the power of pumping a 15w40?


HAHAHAHAHAHAHAHAHA!

How much power do you really think is being lost?

Difference between 10W-30 and 15W-40 on the oil pump drive shaft
= WAY less than 1/4 HP difference!!!
(especially when hot, probably 1/20 hp difference)

Power has NEVER been a problem with my 454.
Gas mileage, on the other hand........
 
Originally Posted By: Linctex
Originally Posted By: Alex_V
You need all the power and as little parasitic drag as possible in that application, so if a stout 10w30 is more than adequate why waste the power of pumping a 15w40?


HAHAHAHAHAHAHAHAHA!

How much power do you really think is being lost?


I wouldn't venture to state a number, but I have witnessed the difference between the two grades of the same oil back to back, in a flat tappet, carbureted 454, so I feel I have some qualification to say: it is noticeable.

I'll grind my axe, you grind yours. Just watch the sparks on the puddle of oil on the floor.
 
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I'm sure it *is* "measurable"....

but in the real world, it's usually not noticeable by the driver.

What does make a HUGE difference is the air temp.

I swear, it feels like I lose 5-8 HP for every 10 degrees F increase.

When it's cool (50*f) it's a ROCKET (impressive acceleration for a 8,400 lb truck
when it's 108*f, it still good but very noticeably less
 
Sadly. I don't think the oil i use will make a difference.

Its a motorhome. So by the time i load it up, get food, hook up the 6k lb boat, i doubt I'll notice the small hp gain of thinner oil.

Once i get on the highway, the motor will be toasty, so even long part throttle driving will be kinda iffy .
 
Originally Posted By: Linctex
Originally Posted By: Alex_V
You need all the power and as little parasitic drag as possible in that application, so if a stout 10w30 is more than adequate why waste the power of pumping a 15w40?


HAHAHAHAHAHAHAHAHA!

How much power do you really think is being lost?

Difference between 10W-30 and 15W-40 on the oil pump drive shaft
= WAY less than 1/4 HP difference!!!
(especially when hot, probably 1/20 hp difference)

Power has NEVER been a problem with my 454.
Gas mileage, on the other hand........

+1
..and one get back the power 'loss' due to 'increased' drag, by revving up additional 30 engine rpm ..
which probably moves closer towards lowest specific fuel consumption point on power curve, thus gaining FE.
27.gif
 
Originally Posted By: leroyd92
I just figured a good syn 10w30 would free the motor up more.

I keep hearing/ reading horror stories about the cam wearing out due to heavy oil and the splash fed systems


Total lie. We toss nothing but 50 and 60 weight at big blocks and never have an issue. Wear is less than 30s or 40s too. 40 is fine for a truck because it'd not going to be seeing 4000 rpm all day long.
 
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