Jim,

Where are you finding these different sizes?
What year size-engine-"make" are you referring to?

Let's assume 235 cubic inch Chevrolet engine?
What year/years 235 engines are you referring to?

Any/all 235s (1937-1962) were 3.85096 liters

So, truncate to 3.8 or round to 3.9

Tim
1954Advance-Design.com
1954 3106 Carryall Suburban
1954 3104 5-window pickup w/Hydra-Matic
The 216 and early 235 engines are not "splash oilers" -- this is a splash oiler.