[AdamIsAdam]

Oh, and before I had an STP filter, now a K&N.

[HWYSTR455]

Originally Posted by AdamIsAdam

Oh, and before I had an STP filter, now a K&N.

Filter media in a K&N is finer, and that could have alone caused the drop in psi. Try a PF24 AC as a baseline for pressure.

Where do you take the psi reading from, filter housing or rear of block? Rear of block is usually 5-10 or so psi less than at the filter housing.

Bearing clearances pretty much dictate what your psi will be, as well as the oil weight.

Thinner oil does find a way to leak easier than thicker, and syn adds to that. Sometimes additives in syn can impact (shrink or swell) rubber gaskets, which is what the balancer and oil pan front & rear are. Same with rear main seals. It should settle after a few heat cycles, if not, you may need to change them.

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[HWYSTR455]

I remember seeing promo pics of a bug on the pole in the snow...

Also, on the K&N filters, in my personal experience, I've noticed you have to change them at least every 3k miles, because they filter so good, they tend to clog, and you will see a drop in psi.

It's possible the thinner oil washed down the inside of the engine and simulated that first 3k miles sooner, but that's just a stab in the dark.

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[madokie]

i run 5-20 wal mart @ 2.74 a quart year round in my 3 vehicles,,40 psi @ 3k is low??? sure you can put thicker oil in for summer but for what?? more psi on the oil gauge??? it takes HP to spin an oil pump.."you only need 10 psi per 1000 rpm" smokey yunick.. soon as WM starts selling 0-20 cheap,i'll be using that too !!!