Hi everyone - have just joined after reading much on this site over time. About four years ago my VR (V6) Acclaim developed a distinctive knock in the engine when starting from cold. Turned out to be a worn balance shaft. It doesn't seem to have got any worse, and goes away after about five minutes or less as soon as the engine warms up and the metal tolerances close. My mechanic says it would cost about $2000 to replace the shaft as the engine has to come out. Accordingly, I did some extensive research and have put the following additives into the oil: 300 ml Engine Restorer 300 ml Nulon worn engine treatment 250 ml Nulon long term engine treatment 300 ml Xcelplus (the original Siick 50 formula) The knock is still there but bit quieter, but the car seems to be running more economically after i just made a trip up and back to north east Vic. Seems to have a little more power too, but I'll probably have to drive bit further to get the full benefit. Anyone like to comment on this issue? Thanks.