<html><body><div style="color:#000; background-color:#fff; font-family:verdana, helvetica, sans-serif;font-size:13px"><div id="yui_3_16_0_1_1444161834809_2759">Your overdrive should positively engage / disengage when the OD switch is operated. It should stay engaged until you move the switch to disengage (unless you shift gears, switch off the ignition, or you are in 1st or reverse). If you want to diagnose the problem, the first thing you need to know is the pressure the OD hydraulic system is making. <br></div><div id="yui_3_16_0_1_1444161834809_4023" dir="ltr"><br></div><div id="yui_3_16_0_1_1444161834809_4024" dir="ltr">I doubt the type of oil is the problem since you have topped-up oil in the GBX/OD. As Randall mentions, low hydraulic oil pressure is a likely possibility.</div><div id="yui_3_16_0_1_1444161834809_6777" dir="ltr"><br></div><div id="yui_3_16_0_1_1444161834809_6780" dir="ltr">I makeup and sell the needed Overdrive Oil Pressure Gauge sets:</div><div class="" id="yui_3_16_0_1_1444161834809_4016"><br class="" id="yui_3_16_0_1_1444161834809_6783"></div><div class="" dir="ltr" id="yui_3_16_0_1_1444161834809_4017"><a class="" id="yui_3_16_0_1_1444161834809_4018" href="http://webspace.webring.com/people/tj/jholekamp/">http://webspace.webring.com/people/tj/jholekamp/</a></div><div id="yui_3_16_0_1_1444161834809_4072" dir="ltr"><br></div><div id="yui_3_16_0_1_1444161834809_4087" dir="ltr">brgds, Jay</div><div id="yui_3_16_0_1_1444161834809_4088" dir="ltr"><br></div><div id="yui_3_16_0_1_1444161834809_4089" dir="ltr">'64 Triumph TR4</div><div id="yui_3_16_0_1_1444161834809_4104" dir="ltr">'62 Morgan +4</div><div id="yui_3_16_0_1_1444161834809_4105" dir="ltr">Wheaton Illinois<br></div></div></body></html>