Grind going into 3rd gear .. Need Oil recommendation

[Onefast99gsx]

Ok, Here's the scoop. I put in 2.5 qts. of straight synchromesh tonight and took it for a beating. 1, 2, & 4th shifted better than it ever has. Very smooth. Third still ground some but not quite as bad. Any grinding is bad though. So i took it home and drained out 1 qt. and put in 1 qt. of Heavy Shockproof and took it out for another beating. To my amazement, the grind was virtually gone. I tried a couple of speed shifts and it was great. The heaviness of oil must help to slow the syncho down. The only bad thing I can say about it, is the rest of the gears didn't shift like butter as it did with the straight synchromesh in.