Straight 40 weight in a Model 'B'

I've had recommended to me recently by some other B, C, and CA owners to move up to a straight 40 weight if your engine is a little clanky, like mine is. Right now I have straight 30 weight in it. Oil pressure starts out great in the middle of the gauge, but eventually peters down to the "low" side after it's fully warmed up and hovers right on the line between "low" and "normal." It is an aftermarket gauge. My old one always read higher and had numbers, but something blew out inside it and oil filled up the inside of the gauge, so I got a new one from Steven's Lake Parts and it's always read lower, which makes me think it's one of those automobile ones that's meant for higher PSI (30+) cars that just has an "Allis-Chalmers" plate stuck in it for looks.

Regardless of whether I have a dud of a gauge, is it crazy to use Straight 40W in the shoulder seasons and summer when it's above 60 degrees F? Want to add that part that I understand winter multigrade oils and how much damage you can do using a straight weight oil below 32F, lol. 

Alright! Commence keyboard flogging!

15 psi is NORMAL at high idle if the engine is in good shape and filter is good.. Pressure with a NEW filter might be a couple psi low untill the filter becomes soaked, and gets some BACK PRESSURE.... The filter and the 1/4 inch tube inside it are what causes the BACK PRESSURE on the gauge.... thinner weight oil could actually be pumped thru the orifices easiler and get you BETTER FLOW to the bearings and spray at the piston wrist pins..

Heavier oil will cause more back pressure in the filter and make the PSI reading go up.. It should also cause higher viscosity in the 85% of the oil going to the engine bearings / pistons... That might not get you MORE OIL, due to the THICKER VISCOSITY....

I would prefer a 10w- 40 of 15w- 40 oil if you think the 30wt is too thin.

I have seen more that one B engine that  runs fine with 10 psi at high idle and 5 psi a low idle..... when you loose pressure on a B-C engine, its normally due to oil pump wear on the end covers... Too much thrust clearance and your loosing efficiency.

You think that's a surprise: once while delivering fuel to a station and a yuppie with his family pulled in to fuel up "daddy's pretty PEV diesel pickup" and left the engine running to run the A/C. Next to him the driver of the car had gone into the store and the filler hose of the car fell out of the car filler neck and continued to flow as the puddle creeped under the front of the pickup the engine. It was hilarious to watch the HORROR on the yuppies face while the diesel pickup quickly rose in speed and continued even after he had jumped in and turned the key off. The Pickup continued to rise in speed until it self destructed in a spectacular fashion. It was worth driving in the DC Metro traffic that night to see that happen. 

Haha that's one of those things you wish youtube & camera phones had been around!  Kinda similar to why any diesel, let alone a jimmy, has a shutdown flapper in mining applications where natural gas concentration may be an issue.