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</head><body>Okay. As usual, I don't totally understand the technology. Ugh! I was an English Major! Then human services administration....<br><br>Is the answer that, since John Esposito put it in, ...that NAPA 30 wt non-detergent is okay? ...Or should I just stay with Mt-90 as all recommend here and use the 3 quarts of NAPA 30 in the lawn mower?I <br>Sorry to be so dense!!!!<br><br>Terry<br><br>> On June 19, 2018 at 5:29 PM Randall <TR3driver@ca.rr.com> wrote:<br>> <br>> <br>> <br>> > So my question. I've forgotten whether it was non-detergent. <br>> > I suspect so,since wouldn't that give it more grip????<br>> <br>> Thing is, the factory switched from recommending motor oil to specifying<br>> GL4. Seems to me they must have had a reason for making the change.<br>> <br>> Ken Gillanders (formerly British Frame and Engine) looked into the reason<br>> for the change, and was reportedly told by an ex-factory engineer that they<br>> were having trouble with premature failure of countershaft bearings/thrust<br>> washers. They felt the EP additives in the GL4 would help protect the<br>> bearing surfaces. Evidently it worked, because they continued to specify<br>> GL4 through the end of TR6 production.<br>> <br>> I can't say whether that is true, but I note that John Esposito also<br>> acknowledges it as a problem on these gearboxes, and offers to sell an<br>> (expensive) conversion to stronger bearings.<br>> <br>> His post about GL4 being too thick makes no sense at all to me. Even when<br>> the factory did recommend motor oil, they specified 50 weight for temps over<br>> 70F. 50 weight is actually thicker than 90 (at the same temperature)!<br>> (They are rated on different scales, which deliberately are offset from each<br>> other. No such thing as 50 weight gear oil, nor 90 weight motor oil.)<br>> <br>> -- Randall<br>> <br></body></html>