My researched and scrutinized opinion is that the best filter available is the Fleetguard LF3487. It is an expensive ultrapremium "no expense spared" filter probably overkill for the short intervals most of us change our oil at. Wix 51806 (NAPA Gold 1806) and its equivalent from Purolator contains a built-in standpipe to keep (more) oil in the filter in base-down mount applications like the slant-6, for faster lube on cold start.

But those are harder to find than NAPA Gold 1515, Wix 51515, Purolator L30001...

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Here is an on going deal on Wix. http://board.moparts.org/ubbthreads/sho ... &fpart=all

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'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto Dually Clubcab needs a injector pump
2005 Golden Couch Buick

Thanks for the link, I just purchased 8 filters. It seems like the best one for the Slant 6 is #51806.

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Harry
1975 Plymouth Scamp 225/904/8.75
1968 Plymouth Road Runner 383/727/8.75

Just completed service. No difference. No gunk, I cleaned it anyways.
At running temp cruising at 65 mph = 35psi, idle at a light in drive = 10psi.
Both are within spec, but definately on the low end...
I do have a Mopar high pressure pump spring....perhaps I should put it on?

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Harry
1975 Plymouth Scamp 225/904/8.75
1968 Plymouth Road Runner 383/727/8.75

the hp or hemi spring will give 75psi on a fresh engine

But will not make any difference at idle.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

And for fifty points, can anyone tell us what 75 pounds of oil pressure will do for us, other than increase parasitic load on our engine and stand us a very high chance of destroying our oil pump drive pinion?

…class?

…anyone…?

…Bueller…?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Running (exactly) what brand and grade of engine oil, and what filter? Do you get any rod knock at all on a cold start when the engine first fires? Does the engine consume any oil between changes? How much, and how often do you change the oil?

A low-miles engine does not necessarily have nice tight bearing clearances. A great deal of engine wear can happen in an extremely short time by several circumstances. All it takes is a few cold starts by one boneheaded owner back in nineteen seventy-whatever who decided that multigrade oils are the devil's work and straight 30-weight was better (or that 10w30 is communist propaganda and 20w50 was better) -- for just one example of how it can happen.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

It will keep things lubed properly when the tach goes above 5000rpm for your 1/4 mile of fun at the track....on the street, nothing good.

Running (exactly) what brand and grade of engine oil, and what filter?
10W-30 Castrol GTX, Fram (I know, I just purchased Wix #51806)

Do you get any rod knock at all on a cold start when the engine first fires?
No rod knock at all.

Does the engine consume any oil between changes? How much, and how often do you change the oil?I haven't noticed oil consumption. I just bought this car in Oct. '11.
The oil has been changed once by me - I only put about 800 miles on it.
I have no idea how often it was changed in it's first 47k miles.

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Harry
1975 Plymouth Scamp 225/904/8.75
1968 Plymouth Road Runner 383/727/8.75

Much as I dislike and distrust Fram filters, I think it unlikely the Fram filter is restricting oil flow sufficiently to give the readings you're getting. It's possible, and easy to check, but not too likely.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

It's a crap shoot. After I rebuilt the engine in my van I had less than 20 at idle, not much more driving. Rods rattled every morning. Did my 500mi. change and went to a Purolator. That was Jan 2001. 150K+ on it and it still runs great oil pressure.

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'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto Dually Clubcab needs a injector pump
2005 Golden Couch Buick

I concur here, my father-in-law did an oil change on his 94 Dodge Diesel,
used a fram filter...then complained that his oil pressure was about 10-15 psi low....Told him to swap immediately to a wix or Napa Gold filter...did swap, topped the oil level off, pressure returned to normal...

So it's worth a chance.

-D.Idiot

Remember folks, for the Slant Six, the factory service manual states "minimum oil pressure at idle 8psi, operating pressure at 2000rpm 30-70 psi"........

Mind you, I'd like mine a little higher than the very low range however it's kosher where it's at - although barely. We'll see, I will change the oil again, use 10-40 and Wix filter and report back.

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Harry
1975 Plymouth Scamp 225/904/8.75
1968 Plymouth Road Runner 383/727/8.75

Yes...which was written to guide dealerships all over the country in all kinds of weather with all kinds of (grossly inferior 1965) oil, in making their determinations whether an engine is in need of extensive mechanical repair -- a decision that directly influenced Chrysler's bottom line (warranty costs). With hot, thin oil, you might expect to see 10psi or even 8psi at idle on an engine with a fair number of miles on it that's still in basically sound condition. But 8psi is really quite low and I think there's a sound case to be made that it's not adequate.
10w40 oil is not a wise choice, number one. Number two, if you are trying to diagnose a problem it's best to change only one thing at a time. Swap the filter and leave the present oil in it. If the pressure goes up, you found the problem. If you go to a heavier oil weight and the pressure goes up, then all it tells you is there's excessive clearance somewhere in the engine and/or oil pump bleeding off oil pressure...and you already know that.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.