Just did my yearly oil change my 69 coronet; Went from Rotella T 15/40 to Rotella 5/40 Synthetic...

Oil pressure still on the high side, 80lbs cold idle, 45 hot idle after 20 mins and a couple of high rpm highway runs, temp at 170, outside at 60ish.

Any thoughts on this oil? Was looking for slightly lower oil pressure on fire up, not finding it.

Any additional additives needed for flat tappet 550" lift cam?

Thanks for all input.

I was running the Rotella 15W-40 but switched later to GTX 20W-50. I have a .509 cam and usually throw in a bottle of the Comp Cams break in lube. However, I bought a bottle of Lucas Zinc additive the other day at Napa for $12. I only change my oil once or twice a year because i don't drive the car much so I don't mind spending $12 on a zinc additive.

BTW, this is in a decently built 440. I have about 70lbs @ startup and around 50lbs @ hot idle. Not sure if I answered anything but hope it helps you in some way.

I have run Rotella, I went with Valvoline 20/50 VR1 just the other day, 70psi on startup warms up drops to 40psi then will go between 50-70psi depending on how much your foot is in it. The Rotella got black in my car after a summer. I think it was probably a tunning issue and not the oil. I run it in my truck and I cant make it black in 4k miles.

I wouldn't worry too much about 80 PSI cold idle unless it goes over 100 when you rev it. Hot pressures sound fine.

The Rotella is probably fine at spring pressures used for .55 lift. I run Rotella plus STP for a little extra zinc and insurance though.