Anyone see Penn Plat 5w-20 at a national chain?

[Rodbuckler]

quote:

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Originally posted by Gary Allan:
...vast array of circumstances since the span of operations make both look like the other in a good bit of operation.

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This is where we differ. I don't think that there are any circumstances where both oils will look the same to the engine, even though the oil viscosity in the pan might be the same. You have to look at how well the oil flows in the hotter pressurized state at various key points in the oiling system.

I can see this from the changes in power loss to the oil pump in my Ford 4.6L with 30 vs 20 weight oils. The 4.6L was designed from scratch for a 20 weight oil of course. There is no operating condition where a typical 5W-30 makes more power than the 5W-20 I using now. That is the 5W-20 makes more power cold than the 30's make hot. The 30's are always sluggish, and the 20 is never sluggish.

I notice the same when using thicker oils in my 351W as 5W-30 works exceptionally well. The thicker oils are sluggish all the time, hot or cold, compared to the medium-thin 30's.

 

[Gary Allan]

Yes, but you don't know what is making them sluggish. Is it the viscosity that is same (your words) ..or the conditions that are making them near in visc (obviously different operating conditions).

Sorry ..9.6 CST is 9.6 Cst regardless of what lable it has on it. Talk to the three Brookfield Brothers (I think that they're all dead) if you don't agree.

If you can actually measure two near viscosity oils for the fractional hp loss ...you need a job as a human butt dyno.

More power to you, pal

 

[Rodbuckler]

quote:

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Originally posted by Gary Allan:
If you can actually measure two near viscosity oils for the fractional hp loss ...you need a job as a human butt dyno.

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Where do I sign up for this job? I'll take it!

You just can't say that 5W-20 at 180F and 5W-30 at 200F in the oil pan (same cSt) work the same up in the engine. They don't. You need to add about 100F to the pan temps and recalculate the viscosities when cold, and use something like the HTHS viscosity hot.

 

[Gary Allan]

I don't know where you came up with the formula there ..but HTHS (150C)you're looking at just about as close as two different weight oils can get. You're at near unity depending on how far the real spread is between the particular 20 and 30 weight.


Can you help me out there? I mean it may be a perfectly valid thingy ..but you lost me in the mix there.

 

[Rodbuckler]

quote:

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Originally posted by Gary Allan:
I don't know where you came up with the formula there

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Ahh, who knows....

It's just that the power consumption doesn't seem proportional to the kinematic viscosity. I will take a set of measurements on my 302's oil system with stock pump, and try to figure it out numerically. I should have done this a long time ago anyways.

 

[Gary Allan]

Rod....just what does a 5w-20 look like visc wise @180F??

What does a 5w-30 look like @ 200F?

Do you think that every engine of this make never sees both (either) 180F-200F temp with both 5w-30 and 5w-20 AT SOME POINT???

otherwise you've got magic oil that skips part of the process

You can have a 20F shift in sump temp just due to ambient temps. This should index itself across the entire engine for the most part. That is, 20 cooler oil should not be as warm at the same rate over the same surface on its exodus. It may pick up more available btu's due to the differential increase.

There's very little difference in the visc of a 30 weight and a 20 weight. It only takes a slight shift in temp to make either look like the other (colder for the 20 ..hotter for the 30). This happens to every oil in every unregulated sump.

 

[Captain Howdy]

Anyway...it's been scarce here at the Wally Worlds. No 5w-30 in quarts either. Mostly 10w-30 in jugs.

Plenty at AA but I don't want to pay that much if I don't have to.