Well, you will see more gauge pressure, but that won't change the fact that your motor is wearing out.

Rich

 

If your going to get oil, you might as well move on and get modern oil that lasts longer, has more "good" chemicals in it. I have heard many story's about motors being completely clean that have ran synthetic oil in them since they bought them. Also check out a website I think its claled bobistheoilguy.com

 

I prefer Mobil 1 synthetic 5-30W changed (with a new filter) every 3000 to 3500 miles.....Iv'e pulled apart plenty of my engines that had ran nothing but that mobil 1 from when they were bran new only to have "everything" including the bearings look almost like new(perfectly clean also)......I personally don't bother with the mobil extended protection oils like the 5000 7500 15,000 mile versions (not that there not good, I believe they are) but IMO, your oil filter is completely shot after 3500 miles anyway, and if I have to get under a car to put a new 10 dollar oil filter on, and add a 6 dollar quart of oil, I'd rather just completely change the oil and filter...........

 

it runs strong, he had a 383 Stroker (stock cam, heads, ~320 rwhp) in it before then put the original motor back in. The original motor has about 120k on it. I realilize it's a 12 year old car, but the accesorries are going to fail before the LT1 does. I'm just hoping it doesn't fail till after college when I can afford to build up a 383.

 

To awnser your question, you really shouldnt see a difference between a 5W30 and a 10W30 oil, other than on a cold start.

When I say switch to a thicker ( To maintain a better idle oil pressure ) I mean go from 5W30 or 10W30 to a 10W40.

Really, with a synthetic, even a 5W40 would be ok.

Alot of people on here shoot for a wide weight spaced oil (If its synthetic) because having the low first number (Cold viscosity) alows oil to circulate faster on a cold start, where much engine wear occurs. This is probably why M1 works pretty well. It is very thin for a 5 or even 10W30 oil.

Once it warms up, the viscosity will thicken to the second number, such as a 30 weight. This is where I personally would be picking an oil that gives me at or above 20 psi hot idle. The lower the idle oil pressure when hot, the less oil that makes it to the pushrods, rockers, pivot ***** ( On stock rocker arms) Trunions on RR's or roller bearings ...

And lastly, dont forget that an oil filter can affect oil pressure mroe than the actuall weight of the oil can.

Hope that helped some.