Is your DTX .18 worn out? Warrenty expired? New engine too expensive? Convert it to an O.S. 15...
You will need the [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXGYC5&P=7]piston/sleeve[/link], [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXCF32&P=Z]con. rod[/link], and[link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXCS77&P=Z] pin[/link]. You will also need a Heatsink for an OS .15, such as [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXDRV8&P=7]this one[/link]. Total for these parts from Tower Hobbies: around $65. This conversion makes your engine more reliable and longer lasting. The newly-converted engine must be broken-in using the [link=http://www.osengines.com/manuals/15cv-cv-x-manual.pdf]O.S. INSTRUCTIONS[/link].
I have done this swap to the DTX .18 myself, and it works great.