control routine 300 switches valve 80 at step 350 and at step 360 the automatic transmission fluid regulation mode is entered while the listed temperatures are preferable other temperatures may be used in step 320 and 325 to determine when the control routine enters step 350 for example a lower temperature of 160 degrees fahrenheit 71 u00b0 c may be used in step 320 preferably the temperature setting in step 320 should be below a setting present for thermostat 50 to ensure proper operation of routine 300 fig1 is a graph 370 showing a first timer setting 372 verses the starting temperature in this case engine coolant temperature ect 374 at engine start up at very cold engine coolant temperatures below a low temperature set point preferably 0 degrees fahrenheit u2212 18 u00b0 c the timer t 1 is set to a high timer value preferably 10 minutes as shown by line 376 between the low temperature set point and a high temperature set point preferably 0 u2212 18 u00b0 c and 15 degrees fahrenheit u2212 9 u00b0 c respectively timer t 1 setting changes as shown by line 377 as a variable timer value preferably between 10 and 0 minutes intermediate points on the graph are preferably derived by interpolation above the high temperature set point timer t 1 is set to a low timer value preferably 0 minutes as shown by line 378 alternatively more set points are used to define the relationship between timer t 1 and the starting temperature fig1 is a graph 380 showing a second timer setting 382 verses the starting temperature in this case engine coolant temperature ect 384 at engine start up at very cold engine coolant temperatures in.