engine oil capacity

[kully 560]

this seems like a dumb question but on a f54 block and a n47 head I can only get 4.25 -4.5 qt of oil in this motor. I drain the motor oil when it is hot, I let it drain for about 1/2 hour then I  change the filter.  now I fill with 4 qt of oil ,start it up bring up pressure and then I shut down and let it cool for about 1 hour or so and then I check it and it only takes maybe a 1/4 qt - 1/2 qt more to top it off to high line on the dip stick.  every book says 5 qt but not in this motor. does every body get in 5 qt of oil? I check the rubber stop on my oil dip stick and it does not move so I now that is not the problem. I just do not want to dump in 5 qt and it shows over filled also.

[Zed Head]

It's the oil pan that determines capacity.  Assuming the oil pan matches the block and head, you just need to use the right book.  And maybe the right filter.  Are you using one of those new mini filters?

The dip stick is the indicator for proper level for the bearings, without aeration.  I'd be happy with that.

 

[siteunseen]

5 quarts is too much for mine, but just barely and I use the full size Purolator filter.  

Edited January 29, 2018 by siteunseen

[Zed Head]

The 280Z's are spec'ed at 5 quarts.  The OP has a 280ZX engine.

Then there's always slope of the driveway, both when draining and checking the dip stick.  Oil expansion too.  If you add it cold, then measure it hot it will show more than what you put in.  Oil expands a lot.  Like when you pop the fill  plug on a warm transmission.

https://www.engineeringtoolbox.com/cubical-expansion-coefficients-d_1262.html

http://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT77.pdf

 

[kully 560]

I do the oil changes in the garage level floor.but the f54 block is a turbo block from  a 1983 zx.  I swap the p90a head for the n47 head along with the oil pan which both came from 1977 280z motor. the reason the oil pan was swap is because of the oil cooling line that is use on the 280zx turbo motor. so I  thought the z motors all took 5 qt to fill up?  (large filter ZED HEAD) I DO FILL PUT IN AS MUCH AS I CAN UP TO THE HIGH LEVEL MARK. so adjusted to the newer trucks and cars it they take what it states in the owners manual.
 

Edited January 30, 2018 by kully 560

[Zed Head]

Here's something interesting.  An F54 block dip stick is 6 7/8" inches from the High mark to the rubber seat.  An N42 block dip stick is 7 1/4".  So if you had a 280Z dip stick in an F54 block you'd be low on oil, because the High mark would be lower.  Probably a lot more than a fraction of a quart though.

Looking at the dip sticks does make me question their accuracy though.  It's just a rubber seat on a piece of metal.

[kully 560]

I measured the dip stick and yes zed head it is 7 1/4" down to the top of the rubber stop.  when I changed out the oil pan from the 1983 zx motor to the 1977 280z  motor oil pan I used the 1977 dip stick to match but never thought the was going to be such a difference. what is you thoughts on how to correct this  problem?

[Zed Head]

You could re-mark your dipstick, or get an F54 block stick.  The dip stick is designed to indicate where the oil level is in relation to the crankshaft and oil pickup, which are tied to the block.  You could install a 50 gallon oil pan, but the dip stick would not need to be changed.

You err'ed when you switched dip sticks.  Not a huge error though.  The difference between the two is 3/8", which is still within the range of the H-L limits on either stick.  So if you keep it topped up, you won't run low.  If you let it get down to L though, it would be below the L on the proper F54 stick.

Edit - the good news though, is that you were right to ask the question.  There's something wrong.

 

Edited January 30, 2018 by Zed Head

[kully 560]

yes this has been in the back of my mind for years but I all ways figured I was in range ! I all ways thought the blocks and pans were the same and I picked the better looking dip stick never thought about  matching  them up. so what 50 gallon oil pan?

[Patcon]

4 hours ago, kully 560 said:

so what 50 gallon oil pan?

He was making a hypothetical. Doesn't matter how much the oil pan holds. Only the level relative to the crank shaft.

[kully 560]

yep I ordered a zx dip stick so I let you now how it works out zed head thanks 

[kully 560]

hi zed head I pick up a new 280zx oil dip stick part # 11140-p6502. it is the same as the one I had in the engine. (nicer looking with yellow shrink tube on top. haha was not a loss $ 15.00 shipped)  so with 4 1/2 quarts of oil and the large oil filter the reading just touches the h on the high level mark. my Chilton's book says capacity  is 4.75 qts and the Haynes says 10 pints and on the nico forum somebody posted 4.25 quarts. there is no way to put in 5 quarts of oil with out it being over filled . I am just going to fill to the high level mark but it still bothers me that there is a 3/4 quart difference between the 3 references.