Try 20-50 and use a Wix filter, NAPA is a Wix and will work as well.

I agree 25 is plenty at idle I missed the in park part.

best oil
 

Brad Penn 20W50. Ask any of the many customers about this oil. You'll be glad you did.

what oil to use
 

I would suggest valvoline RACING OIl, 20-50. your dealer might have to order it but is good stuff and not real expensive. make sure you specify racing oil or you will get the regular valvoline. this race oil also has the proper amount of zinc in it which is a big problem with oils today (no zinc) which ios a big problem when breaking in flat tappet cams( they wear out lobes on the break in. good luck. PS you may stiil want to see about a better oil pump or check the other things that cause such a big pressure drop like yours

I must ask.... I keep hearing about "Brad Penn". I have used: Redline, RP, & Mobil 1, all with good results. So, why is Brad Penn so great? What's the compelling reason to make it so great? Also, if i run Brad Penn, will I see an increase of pressure VS other brands? Gimmie the scoop... is it also synthetic (Brad Penn)?? I have a BBC solid/roller w/ a remote oil system & I get about 20psi @ idle when hot... off idle is 50+ & never had issues. I must admit, I would like to see more pressure @ idle when hot however. I have big hooker headers, & you know how a bbc in a 1st gen Camaro is... not much room, gets very hot in there, I use a dual remote mount K&N filter.

Brad Penn
 

I could post all the engineering and test data that Brad Penn publishes concerning their oil(s), and we could discuss which oil is best, which oil is marginal, and all the reasons why.

The best advise I can give you is to ask your fellow racers that use Brad Penn why they switched. I will tell you that every engine I assemble with flat tappets, gets Brad Penn oil and ZDDPlus oil additive.

Ask around, then you make your choice. Let us know the results.

Where do you get Brad Penn?

The Brad Penn 20/50 is priced very competitively and works GREAT. I have used Pennzoil and the Valvoline Racing oil in the past, but the Brad Penn keeps its consistency longer. Even in my 468 that ate itself up after 22 passes the oil looked just like it did when it went in the motor. You just have to get used to the green look...lol...

Anyone tested the Brad Penn as of late ? I've heard that its changed and isnt as good as it used to be ?