What is interesting is that having spoken to the late Awful Dave Williams a long time ago, I fitted a car type cartridge filter to the Red Thruster. When it was fitted was immediately after the UFM had been cleaned out by way of a ferkin great hole in it, and after the elastic band job had taken place. I( It's been in MPH ) fitted a new paper filter in the normal place and fitted the car type jobby in the return line before the feed to the rockers. After the usual running in, ha, ha, ha, and the usual obligatory oil change after 250 miles, I went on to do 2,000 miles more and then removed the paper filter which proved to be absolutely spotless!!! The car cartridge was cut apart and found to be full of all sorts of detritus, certainly there were three colours of metal in there, horrifying, but good to know that it had done it's job. Needless to say, the tricycle already has one fitted. Cheers, ET43