More Info on Spectro Oil for Sportster Chaincase
I was at an aftermarket HD parts/repair shop this afternoon to pick up some of the GL1 for my Sportster chaincase. The owner (I think) said that he didn't believe that the GL1 was the best choice for the Sportster transmission and that they always used the GPCL (Heavy Duty Gold Primary Chaincase Lube/Transmission Lubricant). He called John Dunn at Spectro to confirm. (John has been at Spectro for over 25 years.) John said that while the GL1 wouldn't do any damage, the GPCL was formulated for the purpose and that is what they recommend. I checked the website and the description for the GPCL says "Heavy Duty Gold Primary Chaincase Lube/Transmission Lubricant is the ideal choice for all Big Twin and Sportster chaincases. It is also made especially to provide smooth shifting in Sportster and all Big Twin transmissions."
Based on that, I'm going to try the GPCL. It's cheaper and it's what the long timers seem to believe in.