Jumping from oil pressure to bearings..................to oil pressure!!  An ideal lubricating oil in an engine would have the same viscosity no matter what the temperature but in the real world the oils get thinner as they get hotter.
Because straight weight oils have such steep curves for viscosity verses temperature, the multi weight oils such as 15W-40 were developed.  At 0 degrees the oil supposedly mimics the viscosity of normal 15W oil and at 100 degrees the oil mimics the properties and viscosity of 40W oils.  The multi weight oils only flattens the viscosity curve for the oil.  Even so called multi weight oils get thinner as they get hotter.

wiki.anton-paar.com/en/engine-oil/

Scroll on down the chart until you get to the 0W-30 and straight SAE 30W charts.  Notice the red graphs on the right hand side that show the viscosity of the oil related to temperatures. Note how much flatter the curve is for the 0W-30 compared to the standard SAE 30W.  The multi weight oil will be thinner at 0 degrees than the corresponding SAE 30W yet are very similar in viscosity at the higher operating temperatures. 

 D4Jim, thanks for that link, very interesting, I've always thought oil get's thinner as it heats up, that's why we change it when the engine is hot, but when I talk to people about 15W40, like I use in my Case tractor and Landcruiser truck, I get told the 15 is the "thickness" of the oil when it is cold, so it flows quickly around the engine when it's cold, and the 40 is the "thickness" when the oil is hot, but that seems the reverse to what I see, maybe you can explain it better.
Thanks
Mike

the thing about multi grade oils is they the thickness of 15 when its cold and the thickness 40 when it is hot meaning the oil is as thick as cold sae15 and when hot its the thickness of hot sae 40. the reason was no need to keep 2 different oils or dilute them with kero which ruins it actually. and have to change oils for winter and then for summer even though the machine hadnt done enough work to warrent a oil change. the oils contain temp sensitive polymers and thickeners to affect these changes.

and you can use modern oils in these old engines just fine simply get a recommendation from the oil company.

if your really worried get the white metal bearings recast then have fun scraping the bearings to get them to fit properly it is a lost art. ive seen white metal being cast in place never done it though.

Mike--I still have a couple of those new old stock stewart warner gages--mine were made on 3/60 and have a part no 2H2317 which i think is Cat's No.

Thanks guys for your input, I had a good chat with Eddie (Edb) the other day and he mentioned that in his opinion the oils we use now in our trucks and Cats, like 30W or 40W, or 15W40, appear to him to be thinner than the same weight oil from the past, like the 30W oil being sold in 1939 when my D4 7J was built in 1939, is probably closer to a 50W, or even 60W engine oil of today.

I know when I've dragged a old dead Cat home in the past, the first thing I do is drain and flush the compartments, the engine oil is always horrible, usually there's a 2" thick layer of carbon crud laying in the sump that needs a chisel or paint scraper to remove, the gearboxes are often water contaminated, yet when I get to drain the final drives, the old oil comes out looking like golden honey, it's beautiful, and slow flowing more like a 320W, often with no contamination, and I've often wondered if it was the original oil from new, because most farmers wouldn't waste money, and good oil, in areas they didn't see the need.

It's a bit like I've pulled pistons on old gas Cats and I'm sure previous owners have simply rotated the compression rings from top to bottom, rather than fit expensive new rings, because the bottom compression rings will have half a inch end gap, while the top compression ring has 1/3". When money is tight, and it often is when farming, people do interesting things to keep a machine running, like filling final drives with grease, rather than fix the leaking bellow seals! LOL
Mike

dad has done that to gearboxes on slashers and water winches make a porridge of grease and heavy oil to slow leaks up.

Mike=

Regarding Bill Glenn's thread I think this this is the URL:

www.acmoc.org/bb/discussion-d72/5708-tra...od-journals?start=30

In reading some of the thread (Still haven't figured out the search system) it appears he ended up not using his fabricated inserts.

Daron

Thankyou daron for finding that old thread, made for interesting reading again, when I saw the photo of Bill's gorgeous daughter under the tractor polishing the crank, it reminded me of seeing it 10 years ago.

It was interesting seeing all those old handles again too, guys we don't see any more, like SJ and ccjersey.
Thanks again
Mike

Just a update to this thread, thanks to everyone who chimed in, particularly "Josh" who provides us with brilliant cross references to old and new part numbers, I managed to get the new bearings from Florin and they just arrived at the Post Office today, 3 weeks from Sacramento to Australia, and they look perfect.

Once it stops raining I'll check them out with the plastigauge and get the sump back on that D4, fingers crossed that fixes my low pressure issue at idle, initial measuring with my el cheapo digital vernier shows the new bearings are around 2 thou thicker than the old bearing shells.
Thanks again
Mike

Hi Mike,
0.002" thicker would mean 0.004" closer/tighter fit on the diameter--anything has to help--"ouch" said Mike's wallet but, at least you now have them in hand.
Max. dimension for the D4400 big end clearance is 0.013"---standard new is 0.0055" to 0.008" so now we are hanging by the finger nails to know the actual clearance you measure with these new "U beaut" mega $$$$ bearings--and the new oil pressure reading when hot ))

Cheers,
Eddie B.