rt138RT-138. Product Details. Catalog Page 2064. Brand RED HEAD. System of Measurement Inch. Material Steel. Finish Plain. Anchor Type Female Threaded. Compatible Anchor Size 38DATA & SPECIFICATIONS RT-138 Issue 1, Page 11 13 Cylinder oils of excessively hh BN for the fuel sulphur can lead to excessive piston crown deposit accumulation. Piston crown deposits need to be carefully monitored