Posted by Ken Dunnington on Monday, November 07, 2005 at 2:52PM :
In Reply to: Correct fluid for NP205? posted by Joe Cimoch on Monday, November 07, 2005 at 6:43AM :
It should be GL-1, not any of the gear oils that have EP additifes(like GL-2,3,4,5). This info has been around for sometime now. That old 90W for the hypoid differential is not what should be used in transfer cases and transmissions. SAE 50 engine oil is recommended as well. SAE 50 engine oil has the same viscosity as 90W gear oil, but doesn't have any of the EP additives. That said, it's not likely many folks will find SAE 50 readily available though normal retail outlets.
The EP additives cause two problems, they are a bit large in size and thus can actually 'clog' areas of tight clearance found in places in tranfer cases and transmissions. They also can react with any bronze parts like bushings.
I know, we all have had x number of transmissions that ran x number of years with the same lube as the diff, but it's old news that this is not the best scenario. If you want to treat your transfer case right use GL-1 or SAE 50, not the same lube as what goes into the differentials.
Ken
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