15.2.1.8 With the exception of Period 1-5 Historic machines, and production-based machines without a lower fairing which have ADR compliance, all machines, including sidecars, must be fitted with an integral lower fairing dam or separate catch tray, which must be constructed to trap and hold engine oil and / or coolant:
a) For 4-strokes machines, a capacity of at least 3 litres,
b) For 2-stroke machines, a capacity of at least 2.5 litres,
c) With no less than 2 holes, each of 25mm, which may only be opened in
wet race conditions.

That's unique to Aus rules.
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