Oil Pressure Difference

[SoTxPollock]

I've been using Rotella 5w30 synthetic oil since I bought the truck, well I found some of the Mobil truck and suv oil at a great clearance price and bought a couple of oil changes worth. Since switching oils the oil pressure pretty much across the board, except at idle, has dropped by 5 psig.
Whats going on? Any scientific basis for the pressure drop? Actually above 2000 rpm it always ran 67 on the Shell and is now running 60 on the Mobil.
Looking for answers.

[LanduytG]

Very common with a true synthetic. PAO's have less resistance to flow so pressure will drop. But not to worry you are still getting the volume you need. I use Amsoil and it does the same thing. Pressure is always related to flow resistance. It would be like going from a 1" pipe to a 1-1/4" pipe.

Greg

[spongebob]

not to change the subject, but im ready to go to a synthetic, and theres not a drop in my area...

[LanduytG]

We are as close as your phone 888-306-4255. The best by is the 15W-40 in two 10 quart jugs at $82.50 and shipping is around $13. So its still less than $20 a gallon.

Greg

[SoTxPollock]

Well spongebob there you go, ask and ye shall receive. You don't need to worry about changing the subject, we're all good guys here.
Greg are you saying that the Shell Rotella synthetic is not from PAO base stock? I've heard before that it wasn't a full synthetic and my memory is not what it used to be, but I thought Shell and Mobil 1 were of the same Olefin family. I've designed pressure vessels for Poly Alpha Olefins plants for Shell, Texaco, Chevron, Mobil and Exxon to name a few so they all produce the stock. Whether they all use the same or similiar formulations only the labs would know for sure. I would like to see the process specifications for their products and I have in the past, but I think they are all playing the mine is better than yours game right now. Facts are IMHO the worst of them are better than any of the conventional oils for guys that tend to punish their engines by pushing the limits on everything.
Just interject a thought here if it pumps that much more freely does it also get displaced from the bearing surfaces say between the rod and crankshaft bearings that much easier? I know the formulations in conventional oils have been eleminating more and more of the so called contaminating elements some of which possess great lubricating qualities and have heard of a lot of flat tapped camshaft failures lately due to that condition. Of course we don't have to worry about that we got rollers in the DMax, but it bothers me a little with my old firebird engine with the flat tappets, opps drifting off the subject.
Thanks for the reply, sell spongebob some oil now, yeah synthetic.

[More Power]

IIRC, the LB7's I have experience with both run 65+ psi oil pressure down the highway and idle 40+. This is when running either petroleum or fully synthetic. There is a little diff between pet & syn, but not that much.

Jim

[LanduytG]

Delvac and Amsoil are true synthetics (PAO's). Rotella is a mineral oil that has gone through a process called hydrocacking. Castrol started this type of process some years ago and they called it a synthetic. Mobile sued them for it but the FTC said it was taking out of its natural state so it could be called a synthic. So today you have all kinds of oils that claim to synthetic but really are not. They are better than regular oil but they are not the quality of a PAO.

Greg

[spongebob]

thanks greg, ill give you a call asap...