So I’ve been looking around, and every past forum I see is saying 5qts of oil is the max for a 350 or 355, which I agree with since that’s what’s in my manual for my 1978, and that’s what I could’ve sworn I put in my car my last oil change. However, I recently just did another oil change for my 355 crate engine and put 5 quarts plus some in the filter and it came up to the add line after letting it sit for a while. So I thought well maybe since it’s a 355 and not the typical 350 that was in my car stock, maybe it needs more (I’m not a big engine guy so other than basic stuff idk if that’s right or wrong thinking), but I ended up putting 6 qts in and got right to the full line on the dipstick. I thought I was fine, but I’ve been reading that sometimes you can have the wrong dipstick etc. so I really don’t know if I’ve overfilled or not. My oil pressure has gone up a little since this oil change but not much, if that means anything. I also have no papers on the engine as the last owner put it in, but any advice I’d appreciated! I doubt helpful, but here’s some pics of my oil pan and dipstick. Maybe someone can compare and say oh yours is bigger than stock etc. Also don’t mind the mess underneath I know it needs cleaning, just having a small oil leak rn.

 

capacity on a gen 1 sbc is dependent on what oil pan and what size filter is installed on the engine. Being a 355 has zero to do with oil capacity... all that means is it was a wornout 350 that had the piston holes honed out larger so the .030 larger pistons and rings can be installed for a nice tight seal again.. you likely do have too much oil in there which can hurt performance a bit but I dont know for sure.. I dont recognize your oilpan. it looks like the one on my vette but your drain plug is in a different place. my 355 takes 5 quarts with the stock replacement filter. and yes that is an aftermarket dipstick so...

 

I would try to locate a correct dipstick/tube and go with that. No telling what people do with cars over the years.

 

Should I go with a 78 dipstick from zip or someone and try that, or do y’all know of any way to know the specs of my engine for sure, like maybe a website to plug in the block numbers? Just don’t want guess and change something when who knows maybe that dipstick while aftermarket could be the right one for the car. Overall, I’m thinking about just draining it maybe 1/2 a quart to get it in the middle area and trying that. Would be about 5.25-5.5 qts in the car total. I don’t know any symptoms of adding too much oil, but car seems to be running fine.

 

Doesn't matter what the block number are. Matters which oil pan in on that block. Easy way.
Completely drain. Refill with 5 Qts of oil. Remark dip stick.
If dip stick doesn't reach. Pull the tube out of the block and shorten a bit.

 

Measure the length of the tube. FWIW, original in 78 measures 8 3/4" from the shoulder (the flared section of the tube that stops it when seated in the block) to the top of the tube. Determine what length your tube is just to see.

Buying a 78 dipstick will not help if the tube is the incorrect length.

 

it is not the volume of oil. it is the height of the top of the oil. the area of the pan in front of the sump above your steering is above the level of oil when engine is off. otherwise the crank throws are whipping the oil into foam in the pan. wasting power playing mixer, wasting oil slinging too much on the walls and foaming the oil in the pan so the oil pump is pumping aerated oil into the bearings. measure the length of the dipstick. from top of tube to end of stick. measure straight down from top of tube to bottom of pan and top of sump. now approximate the angle the dipstick goes in at. it looks to be close to 45 degrees as it sort of runs along the block edge. if it is around 45 degree angle, 4 inches down is 6.8 inches of dipstick length. so if top of tube is 8 inches above top of correct oil level the dipstick full mark should be close to 13 inches down the stick. the add mark is usually fine. the oil pump pickup is less than half an inch from the bottom of your pan. if you drain the pan empty and put in 1 quart, you would probably see oil pressure on startup. it would probably drop as soon as pump sucked the oil out and spread it all over the lifter valley. view down into an alleged 78 corvette oil pan. see the sheet metal sort of windage tray? that is about an inch above full mark. you can see the dipstick crosses the pan at very close to a 45 degree angle. so the height of the full mark should be able to be calculated fairly accurately.

 

id just put in 1/2 a qt more

then go drive the car and ,not over think it

its a car not the space shuttle

 

Removal & swapping out the dip stick tube is fine on an engine stand with no exhaust in the way and the oil pan off if you have to drive it out from the bottom.

Dipstick tubes are made of thin compromised metal that have a tendency to snap off in the worst location of the engine bay. The tube is a precision fit often a few thousandths of an inch smaller than the hole in the block.
You can't hardly get your hand near it, let alone any tools to try to extract it. There have been numerous posts on here about the nightmare of removing a broken tube.

Having preached all that, leave the tube alone and figure out something different with the stick if you so desire.

 

Read post 7 in this thread. You have power steering, 5 quart pan.

https://www.corvetteforum.com/forums...t-oil-pan.html

 

Thanks everyone for the replies! I ended up taking .75qts out tonight which put me about 25% above the Add dot on the dipstick so I feel better about that placement as I now have 5-5.25qts max in the car. I took a lot of measurements and found the following:
Dipstick - 22 in total and 18.5-19 inches from the end to the start on the handle (basically the metal part that goes into the tube holder)
Tube holder that sits in the block: 7.25 inches accounting for the curve and from the top of the tube to the bottom of the oil pan keeping a similar angle is 19-20 inches
With my dipstick in the tube all the way, the amount that sticks out (amount traveling down to oil pan is 11.625 inches)
Oil Pan - length 21 inches, width 7.5 inches, height (lowest portion to top) 7.5-8 inches, and the tub is 10 inches long from the start of the decline to the rear, and 8.5 inches long from where it bottoms out to the rear.