I had the oil of my '68 350 AT 2bbl Firebird chaned. That you can't trust the oil dipstick 100% due to the tube and its installation is known. The garage replaced the filter and filled in 6 qt - they used an AC Delco PF61. This filter doesn't have a capacity of 1qt. Is the PF61 ok? Is it really a problem if there is more oil filled in, say 1/2 qt?
According to the AMA specs your 1968 350 should have five quarts plus what it takes to fill the filter. I wouldn't worry about being slightly over capacity, others might. Funny, the AMA specs for the 1969 350 is 5.5 quarts plus what it takes to fill the filter. I thought they were the same engine. Maybe the filters were larger in 68 than 69? I always put in a new filter and six litres, we can't buy quarts here anymore, but I think a litre is close to an American quart. You can find the AMA specs by going back to the home page then selecting the 67,68 or 69 page, then technical-AMA specs. All the stock specs for your engine are there.
The PF61 is not listed as a filter for the 68 Pontiac Firebird 350. It obviously fits but I notice it does not have a bypass relief valve nor anti drain back valve. The AC delco filter listed for your engine is the PF24 it also does not have a bypass valve but it does have the anti drain back valve. I use a NAPA gold, I believe they are made by WIX, and yes it has a bypass valve. Some do not like a bypass valve in their filters, some think dirty oil is better than no oil, but that's another can of worms discussion.
No, most of it is up in engine while running. If fact used to run a 1/2qt over in by 1st 68FB. No baffles in pan, and sometimes would uncover the sump on hard street launches with lots of tire spin.
I don't even bother with removing that little half pint...
I used to be indecisive. Now I'm not sure. I feel like I am diagonally parked in a parallel universe. 1968 400 convertible (Scarlet) 1976 T/A - 455 LE (No Burt) 1976 T/A New baby, starting full restoration. 1968 350 - 4 speed 'vert - 400 clone (the Beast!) 1968 350 convertible - Wife's car now- 400 clone (Aleutian Blue) (Blue Angel) 2008 Durango - DD 2008 GXP - New one from NH is AWESOME! 2017 Durango Citadel - Modern is nice! HEMI is amazing! 1998 Silverado Z71 - Father-daughter project 1968 400 coupe - R/A clone (Blue Pearl) (sold) 1967 326 convertible - Sold 1980 T/A SE Bandit - Sold
The 75 pontiac service manual says for V8s (doesn't say which ones so I assume all): If you change just the oil and not the filter you need 5 US Qts. If you change both the oil and filter you need 6 US Qts. However this obviously assumes your filter will hold 1 US Qt. I'm using a PH25 on my 76 400. It will not hold a full US Qt. So changing the oil and filter requires about 5.5 US Qts, maybe a bit more. I expect 6 US qts will a bit overfilled. Too much overfilled? Don't know. There is 4 - 5 inches from the filter to the exhaust so you could put on a filter that holds a US Qt in which case you will need 6 US Qts.
If an engine has too much oil it'll find a way to push it out typically by creating a new oil leak. Once a leak path is established it'll always leak until the gasket or seal is replaced. If you don't see any new oil leaks you're probably fine. I'm not a gambling person, I'd rather just drain out the extra oil.
"No, most of it is up in engine while running. If fact used to run a 1/2qt over in by 1st 68FB..."
Yeah, back in the old days I ran 7 quarts total, in my bracket 455's, when running a stock pan. This was with 50 weight Valvoline racing oil, a bottle of STP, 70-80 psi oil pressure, and pipe cleaners in the pushrods. Shifted at 5000 rpm & crossed a little higher. Never had any oil problems.
At higher rpm, there is a lot of oil pumped to the rockers, especially if you are running thin oil, and not running restricted pushrods. This could easily pump the pan dry, by the end of a 1/4 mile run, or any extended high rpm operation.
Obviously, if all you plan is some under 3000 rpm cruising, 6 quarts is plenty.