Factory oil pressure gauge = ? PSI

[1971Challenger]

Hey Guys,

Did a search and could not find an answer.

I have a 72 Challenger with the factory Rallye Dash. What is the equivalent psi per hash mark?

It has 4 hash marks each 1/4 way up the scale.

My pressure used to be "half way" but a recent oil change to Castrol GTX 20-50 made it drop to barely the first mark.

So was wondering if anyone knew the aprox dash pressure gauge to PSI equivalent.

FYI, I have always used 20-50 weight oil (don't recall what I had in it last year, any oil brand recommandions?) and a Mopar Performance shorty oil filter.

Cheers,
//Tom

[Chryco Psycho]

I believe the top line is approx 80 PSI / 1/2 would be 40 ish so you might be around 20 PSI
I recommend the Z -ALt oil , you could have a bad filter , I have experienced this in the past , I avoid Fram Filter , Mopar is usually fiine but everyone can have a bad day

[OUTLAW]

I agree , I think the factory guage was marked off for 80psi and I have seen filters cause this(not often tho) most filters have a bypass valve in them for when they get plugged up and a anti drain back system so filter doesn't empty itself everytime you shut off the engine. cheapest test is another brand filter and go get a mechanical oil guage to test your pressure with

[Katfish]

This guy measured 1

http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Board=QuestionAnswer&Number=5738540&fpart=1&PHPSESSID=

[MEK-Dangerfield]

This guy measured 1

http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Board=QuestionAnswer&Number=5738540&fpart=1&PHPSESSID=

Thanks for that.   

[1971Challenger]

Thanks for the info guys!

Been looking into oil's. Chryco - would you recommend switching to AMSOIL z-alt for a fairly stock older 360 /380hp crate? (no a solid lifter)

I always though but had reservation of switching to a synthetic. I do know if I have a small leak (and I do have oil dampness in the front of the intake/waterpump) it will make it worse.

Cheers,
T

[Chryco Psycho]

virtually none of the new oils SM spec are designed to protect older flat tappet engines properly so for a few $ I would say yes put in a good oil to protect the engine or you may be rebuilding it .Synthetic can leak past seals & gaskets , Z Alt may be a better alternative , some 20-50 oils are better but they will eat some HP pushing oil that thick