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| | | | Joined: Oct 2014 Posts: 11 New Guy | | New Guy Joined: Oct 2014 Posts: 11 | Which fluid for sag 4 speed. Most manuals call for gl5, but I've read to use gl4
Because gl5 corrodes the brass parts. Also any opinions on synthetics.
Thank you | | | | | Joined: Sep 2006 Posts: 3,596 'Bolter | | 'Bolter Joined: Sep 2006 Posts: 3,596 | From the Novak transmission page, there should be numerous search hits for this debate.
When filling your transmission with gear oil, we recommend that you select a conventional mineral oil or a para-synthetic in lieu of a full synthetic oil. Properly assembled manual gearboxes do not have the thermal strains seen by combustion engines or hypoid gears. Synthetic fluid in these gearboxes, while not harmful, is probably an economic waste.
Hypoid gear oil is sulphurized higher than transmission oil and can be mildly corrosive to the non-ferrous alloys used for synchros, bushings and thrust washers in these transmissions.
An 80W-90, API-GL5 or MT-1 rated fluid is very good. Some claim faster shifts from using a 50W engine oil in their transmission and we do not consider this to be contradicted unless you operate your vehicle in a very warm environment. | | |
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