*** IN STOCK SHIPS TODAY *** RBS stocks O-ring kits for the System 1 spin-on HP-1 oil filters. Every racer should have a spare O-ring kit. This kit includes all the needed O-rings to keep you going rounds and in the winners circle. This kit is Viton and can be used with nitro engines.
Not sure which oil filter you have the HP-1 type has the fins on the cannister and the HP-6 filter is smooth.