PF64 - any reason not to use it all the time?

[Russell James]

Putting this question in the Z28 section, as it's the track filter for the Z.

Question is - is there any reason not to use a PF64 all the time, in any LS motor?

I know they use it in the Z for track days. It has a higher bypass spring, less bypass time with thicker oil at high RPM. And it's required to use at all times in the LT1/LT4 engines, same reason - higher oil pressure, less bypass time.

So, any reason why you wouldn't just run a 64 all the time? I'm specifically wondering about a lightly modified LS3 that sees a lot of track days, and WOT street screwin around.

I've been using a WIX 57060xp and Amsoil 10w30 Zrod. But, I've noticed the XP has a 12 lb pressure differential bypass spring. Which is even lower than the PF48.

So wondering if I'd be better off using a PF64 all the time to reduce bypass time. They really make a big deal in the LT1/LT4 to never use a 48 because of the lower bypass spring.

Any thoughts? I'm not thinking of any reason of why not to use a 64 in any extreme use LS motor. But maybe there is something I'm not thinking of. I think even the COPOs use a 48, so that baffles me too.

[Stephen12ZL1]

I feel like it is perfectly fine to use a PF64 all of the time. The factory uses the PF48R from the factory and on the new crate LS7 I purchased from GM.

[frenchsquared]

That is a level of detail that is over my head. I run the PF64 all the time on my Z28.