Mazda MX-5 Miata Sport 2007 Manual page 746

Fig. 2: Identifying Oil-Fill Plug
Courtesy of MAZDA MOTORS CORP.
3. Inspect if the oil level is close to the rim of the oil-fill plug hole.
NOTE:
4. If the oil level is lower than approx. 12 mm {0.47 in} from the lower end of the oil-fill plug hole, inspect
for oil leakage and add the specified oil.
2007 Mazda MX-5 Miata Sport
2007 DRIVELINE/AXLES Differential - MX-5 Miata
Each vehicle is filled with a specified amount of oil (0.7 +/- 0.1 L)

when it is delivered, therefore, the oil level is lower than the lower
end of the plug hole as shown in the figure. However, this has no
affect on the differential function.