Hard to shift transmission

[ramair]

I have a 1916 Buick that shifts great unless the transmission gets hot. I bought the thick oil from Restoration Supply (Lubriplate) when I changed the old oil it was fairly clean with no metal in it. If I stay local (less than 20 miles of driving the car shifts well both up and down, double clutch of course! However 3 weeks ago I took it on a 75 mile round trip on a hot day. It was 91 degrees out California you know, I started having trouble no mater what I did I could not match the engine speed to the trans shaft without all kinds of embarrasing noise. When I got home I pulled the check plug and the oil was foaming with air bubbles in it and boy was it hot. I suspect that the hot oil was keeping the trans shaft spinning to fast. Another fact is that I can not keep the trans full to the top plug because it leaks out the top shaft while parked so if I keep the trans oil level down 2 inches it does not leak. Any ideas would help, Thank you, Michael

[Mark Shaw]

Michael,

A hot transmission can only be caused by friction or some external heat source. Assuming you don't have your exhaust routed near the gearbox, the lack of lubrication and/or the gear & bearing clearances must be responsible for the heat.

I use SAE 250 Texaco Thuban or Shell Dentax. I have heard that Lubriplate makes good products, but I am not familiar with the lube you referenced as "thick oil". Please clarify.

[Guest TJDV]

I am very much interested in the answer to the question as to what type of oil should be used in a 1916 Buick D45. I just drained by 16 transmission. The old oil was very thick and had not been changed at least since 1957. I bought some 600 weight oil and was going to use that after I put in some kerosene to clean out the old oil. I am also geting ready to put 600 weight oil into the differential. Yes one can still buy 600 weight oil, pours like molasses.

Edited November 8, 2011 by TJDV (see edit history)

[Mark Shaw]

Perhaps this will prevent misinterpretation of lube weights and grades.

Equivalent SAE Gear Lube Grades

<TABLE class=small><THEAD><TR><TD style="WIDTH: 50%">ISO-VG Grade</TD><TD style="WIDTH: 50%">SAE Gear Lube Grades</TD></TR></THEAD><TBODY><TR><TD>46</TD><TD>75W</TD></TR><TR><TD>100</TD><TD>80W-90</TD></TR><TR><TD>220</TD><TD>90</TD></TR><TR><TD>460</TD><TD>85W-140</TD></TR><TR><TD>1500</TD><TD>250</TD></TR></TBODY></TABLE>

[Guest TJDV]

I just looked a bottle of 600W Oil that I purchased from Mac's Auto Parts. The back of the bottle says that the 600W Oil meets industry standards and that the 600W Oil carries a minimum viscosity of 2270, contains no addivtives that could damage soft yellow metals, excellant antiwear and low friction properties.

Mark did clear up a lot with his note on lube weights and grades, as I am really new to this field (both oil and old cars). I think I will be OK but would like one more confirmmation!