The Allstar Performance Radiator Cap (ALL30138) is a Spec R octagon-shaped, recovery-style cap rated 38-42 PSI, sized for standard size radiator necks. This higher pressure rating raises the coolant's boiling point for applications running elevated cooling system pressures. Recovery-style caps allow coolant to expand into an overflow bottle as the system heats and draw it back in as the system cools.
Spec Sheet: Allstar Performance Radiator Cap Spec Sheet (PDF)
FAQ
What pressure rating is the ALL30138 radiator cap?
It is rated 38-42 PSI.
What shape is the ALL30138 radiator cap?
It is octagon-shaped, part of Allstar Performance's Spec R line.
What size radiator neck does the ALL30138 fit?
It is sized for standard size radiator necks.
Why use a higher-pressure radiator cap like the ALL30138?
A higher pressure rating raises the coolant's boiling point, useful for applications running elevated cooling system pressures.

