My understanding concerning the oil bypass in the block is that it is activated based on the oil pressure difference between the oil exiting the block and the pressure returning to the block. I added a really large oil cooler and now wondering if that is showing up as a much bigger restriction and causing the bypass to open bypassing my filter and cooler? I am wondering if switching from the Wix XP to a Wix racing filter might lower the overall resistance in oil flow to keep that bypass closed?
Thanks for your comments

WIX Racing offers a 40 micron filtering, basically none. A K&N is 10 micron and has same or better flow and restrictions as the WIX (Check out Engine Masters Oil Filter Shootout) and you can get them in larger capacity with wrench off end for convivence

a large cooler with appropriate size inlet/outlet fittings, lines poses less restriction then a smaller cooler. I wouldn't run a Wix racing filter on ANYTHING, theres ZERO benefit to them unless you want to filter your oil less. The labeling "looks cool", the 58 micron rating which essentially doesnt trap anything smaller then .0023 isnt impressive. The "extra" burst strength is meaningless to anyone running 100 psi oil pressure or less since burst rating on a regular wix is 250 psi. . Your block bypass should be a 30 psi hd bypass, it would require a 30 lb differential to open fwiw, Smitty

Thanks for your help guys. NO racing filter.
These are "Mercury Blocks" and my builder did not change the bypass valves so they are by default 30 psi bypass valves? Is there an inline gauge I can temporarily install before and after to see what the pressure difference is? Like the fuel pressure gauge I have at the carbs?

If you have a remote filter install a fitting to inlet and outlet of oil flow with gauges. Watch the Engine Master show I referred to earlier, it will show/document and explain everything you want to know. Season 6 Episode 5 Engine Masters

How does the Mercury Racing High Efficiency oil filter compare to the K&N.

Thanks,

Padraig

Just re-watched that episode. I really enjoyed that show a lot. I cancelled my Motortrend subscription when they cancelled all of the shows I watched.
So I am happy using the larger Wix XP filter.
I am going to install a 2nd oil pressure sensor in the line from the thermostat to the engine and see if there's a drop in pressure. I am assuming that the pressure should be the same throughout the system correct?
I may be expecting too much out of my coolers. They are rated for 750 hp and I am no where near that. I run in 70-80 degree water. I do have a 2nd oil temp location after the cooler and it never reads above 145 degrees. That is a pretty wide swing from 230 isn't it? I am questioning whether most of the oil is bypassing the filter and cooler. For reference I have 454's with stock cast cranks with automotive clearances running 10w30 oil. It has been brought up that that alone can create a lot of heat. They run around 60 lbs of oil pressure. When I come down to idle after a WOT run they drop to about 25 lbs.
Thanks again for your help.

Maybe I missed where the 2nd oil temp sensor is? 1 is on the outlet of the oil cooler, and reads 145°f?

If you're concerned, you can measure oil pressure after it leaves the block, and before it comes back in. Check the differntial. As Smitty mentioned...larger coolers will creates less restriction.

I prefer oil filters in parallel vs series for lower restriction, on tighter filter media.

I have one sensor in the line between the block and the oil filter. The other is in the line "after" the cooler. Is it common to have the oil temp vary this much even when the cooler is oversized?

I was thinking the larger cooler would show more restriction assuming the tube size that the oil runs through is the same size as the much smaller stock Merc cooler. Maybe in the fine print somewhere you are supposed to block off the bypass in the block because of the extra restriction or at least upgrade to the larger bypass valve?

A large oil cooler is causing my restriction. God you`re a dumbass.