Teuf

Check out Ferrarichat fellow.

xxxtreme22r

doesn't that only apply to Ferrari's? haha j/k man nice reference.

sb5walker

That ferrarichat article has been bouncing around the internet for several years and has convinced many to use thinner oils. However, the guy is a medical doctor, not an engineer, and he was obsessed with flow and cooling, at the expense of lubricating ability or wear prevention. I notice he added material to the end of it this year which backpedals somewhat, saying most engines should use 30 weight, while some should use 20 or 40. So that's at least a little better than the impression given by his original article which would have everyone using 0W-20 based only on flow. I do agree with him that a 0W-40 and 15W-40 have the same viscosity at operating temp - I made that point myself. And I agree with his concern that you should use a low enough W weight so that the oil will flow at startup in the lowest temps it will see.

The Noria corporation is an independent machinery lubrication consultant, which provides advice to major manufacturers. They are not affiliated with any oil company. And they warn that too-thin oil does not lubricate adequately: http://www.machinerylubrication.com/Read/518/motor-oils They are talking about the weight at operating temp, and essentially criticizing the carmakers for recommending 20 weights for gas mileage reasons only, while 30 or 40 weights would provide dramatically better protection for the engine.

My point is that if oil is too thin for the condition of the bearings, and there is no oil pressure, it's not because of inadequate flow, it's because the viscosity is so low for the bearings that it runs out too easily. If you want oil to make it all the way to the far journals, you have to have some oil pressure. It's that simple. And if you don't have oil pressure, it's either down to the pump not working (possible but unlikely on a motor with 171,000 miles) or there is some gigantic leak in the system somewhere (also unlikely), or your filter is clogged AND the bypass valve isn't opening properly (possible with a cheap filter), or you are using too-thin oil for the bearings, which is probably the case with the OP.

Teuf

MM interesting.

Gunnison , Colorado

If a truck sits for a number of months of inactivity, can that be a contributing factor for low oil pressure? Can a newly changed oil filter get clogged under these conditions?

xxxtreme22r

i don't think it would clog, but there is a possibility (since it is a fram) that the filter media inside could have dried out and disintegrated. But I would doubt that if it were only a few months, but your supposed to change oil every 3-5000 miles or every 3-6 months whichever comes first anyway.

bsk83

Just swapped a freshly rebuilt 3vze engine into my truck.
When Cold the Oil Pressure is decent and moves with throttle. Once it warms up however, the pressure goes down to 1-2psi and does not move with throttle. Changed the Sending Unit and that didn't help. Checked the Oil Pressure with mechanical gauge and it read the same. What else could cause the oil pressure to do this? Pressure Relief Valve? Oil Pump? Or is it that maybe something is wrong with the rebuild? Any suggestions? Oh, I put 4 Quarts Castrol GTX 10/30 and 1 Quart of Lucas Oil in it.

sb5walker

Well if pressure is okay when oil is cold then gets too low when oil is hot, then the oil is too thin when hot. So one thing to try is a decent 10W-40 like Valvoline MaxLife which is part synthetic. Or Valvoline Durablend, or Castrol Syntec. Or even Shell Rotella T6 5W-40 which is the same viscosity as any 10W-40 when at operating temp.

But it sounds like there could be a problem in one or more of the oil passages; an opening somewhere, where there shouldn't be one, and oil is pouring out. If this is the case, anything downstream of the internal leak will probably not receive sufficient oil, and may soon develop excessive wear. I hope that's not the case, but even a conventional 10W-30 should have minimally acceptable oil pressure, which of course 1-2 psi is not.

You might check your coolant periodically to make sure there's no oil in it; if your veezy has an oil cooler (can on the driver side of block, just aft of the oil filter), there may be a blown seal inside the cooler. New seals can be had from the dealer for not much $$.

EDIT: Oh, and leave out the Lucas stuff. Just use a good oil like one of the ones mentioned.

blake.nemitz

i run 15-50 rotella year round to keep it quiet and oil pressure high

sb5walker

I use to use 20W-50 in the summers in Albuquerque, but I don't anymore since I've learned that it doesn't flow very well when cold. I think it's probably best for very high mile motors that are very loose and have poor oil pressure because of it. A freshly rebuilt motor certainly shouldn't require a fifty weight to develop sufficient oil pressure. If it does, something is wrong.

bsk83

Thanks SB5. The one thing we haven't checked into is the oil cooler.

rhill

Wow, this is a fun read. Great info SB. I wonder if that guy ever changed his oil??