After reading a ton of posts about pressure, weight of oil, and manufactors....I did alittle test with my LT1. The car has always had Mobil 1 run thru it since 1995, and now has 190k. Last oil change I bought a large 1 qt filter prefilled it with almost 1 quart of 10W30 and then did 5 in the pan. I checked the oil recently, and its quite clean, much cleaner than it usually would be after 1.5 months of stop and go driving. Another thing is my pressure seems to be still very good for the mileage. Cold idle is low 40's. Warm idle is 20, and cruising on highway is in the 30's. Any other high mileage LT1's with pressure around the same?

 

140K on mine and the same. Unfortunately I have little oil leaks everywhere.

 

Anyone else run 1 qt in the filter and 5 qts in the pan??

 

What filter number was that?

 

I see 30+ at startup, dropping off to around 20 when warmed
Highway cruising is around 35-40.
180k bolt on engine.
Seems to have a very light knock from the bottom end, only heard inside the car. Has had no effect for the last ten thousand miles. Amazing to me that it still holds up so well.

 

After you are done, are you checking the oil level on the dipstick? Factory spec is 5 Qt. with a filter change. Obviously, you only want to fill it to the full mark on the stick. I've found it may take a little more than that, when you use an oversize filter.

 

It was a Fram oil filter, dont remember part number but it looks just like ours but 1 qt instead of the 1/2 qt.
Injuneer....to answer your question. The oil is to the full mark on the dipstick and that was about all 5 qts. I prefilled the filter as I always do to prevent dry filter startup. So, total in the system is 6 quarts. I am not leaking any oil, loosing or gaining pressure, and seems to be no damage. I have noticed a cleaner oil, so far and I have not been on any long trips to check mileage increase or decrease.
One thing I will add is I get piston knock when cold here in New Jersey, I never had that before living in California and Florida. I read that its common....

 

I used to run a long filter on my turbo Dodge Daytona, seemed to help keep things cleaner there too. I'm all in favor of larger capacity filters when there is room to fit them, as long as it doesn't put them too close to headers or make them more likely to be damaged.

Hope you'll put the filter part number into this thread when you get a chance to look again. Fram numbers are nice for cross-reference.

 

Still don't know where your oil level is AFTER you've run the engine, with 6 Qt in it. It should be above "full". I suspect most of us run the larger filters, and most of us fill the filter before installing it.... I know I do. But it doesn't take 6 Qt., even with the oil pan dinged out a bit to clear the stroker crank, and a full 1 Qt. Moroso racing filter.

I just want to make sure people don't read this and start over-filling the crankcase.

 

Ok, I cant see the part number but I believe its the PH5 filter. It looks identical to the PH30 or PH25 I cant remember the stock LT1 number....but its just a longer filter. I have a stock ride height car and I can see that it sticks down alittle lower than the stock stubby.
The last post, to clarify. I prefilled the filter with 1 qt. Than filled the crankcase with almost 5 qts. The oil level is at the full mark for my dipstick, but not overfull. I understand the concern because I too dont want people filling their crankcases with too much oil . It was a little test I did to see what would happen, and for me everything seems to be working out great. My car has 190k on it, so I am not worried too much about damage, mostly because the engine has already passed the point of no return. Do you know if the stock relief spring is set to 50 or 55 psi?