i have read alot about redline shockproof for the tranny. the stealer put syn3 in all three holes for my 1000k. 06 xl1220c. what grade of shockproof is best for a sportster?? due to the temp in texas i would guess the lightweight. any help is appreciated.

 

put 75w-90 gear grease in the trans.

 

I finally decided to go with Redline heavy in the tranny. For higher ambient temps you want a thicker fluild. In all honesty, I couldn't be happier. A superior product!

 

What does your factory service manual suggest?

 

Mobile synthetic 75/90 gear oil.

 

I have the shockproof in my 02 twin cam dyna. Seems to quiet the clunk when the transmission is warm. I checked it at about 8K miles the other day and it was as pink as ever. I recommend. I also used Red Line MTL in the primary. It really smoothed out clutch engagement so I am a believer. Red Line 20W50 in the engine hole. 5K oil changes and only added about 1/2 pint toward the end. Gas mileage is improved, oil temp is lower. Recommend.