Another reason for the oil immersion heater is about this time last year it was about 0°F. I cranked up my 7.4L and it was knocking really bad. Before I fired it up I had ran the 5,500w coolant heater for the normal amount of time, then continued to run it for about 5 minutes. Because I thought it might be air in the lifters. After it didn't go away I figured it could be a rod bearing.
A few days later when it was 40°F I went to fire it up to trouble shoot the knock and it was gone.
It was a collapsed lifter that was full of air.
Later when I tore the engine apart I found an air bleeding lifter oil galley plug had been clogged up with a chunk of oil sludge. So the air could only escape from the lifter oil galley when it was some what mild out.
So cold oil does you no favors.
1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost.
1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 4th Gen disc brake fbody rear end.