I hate even asking this but what is the best oil to be running in my tranny. I have an '04 Fatboy with approx. 7000 miles on it and have not yet dropped the tranny oil. Because I bought it used I am not sure if it has ever been changed. I have noticed that since purchase the shifting has been rough and finding neutral can be a b*tch.
Now I was told that synthetic 20w50 would suffice due to the somewhat cooler climate here in Canada which during riding season averages 75 - 85max.
So is this correct or should I be using 75/90 synthetic?
Some of you more experienced types might be rolling your eyes but I had to ask.

Thanks in advance


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You can use a 20w-50 if you would like, that is the weight of oil that HD puts in with Syn3. I personally dont think that it has quite the shear resistance of a synthetic (real not syn3) gear oil. That being said I would go with a mobil 1 75-90. But any major brand full synthetic will do the same. oil brand is your preferance.

Chris

 

I would use Synthetic for sure. Brand is up to you. I prefer AMSOIL but Mobil is a good oil also. As for the weight, Gear oils and Motor Oil weights are measured by a different scale. A 75W90 Gear Oil and a 20w50 Motor oil are the same weight. Here in CA it gets pretty hot in the summer. I run a 75W140 Gear Oil in my 03 Ultra. It is quieter and shifts smoother. 75W90 should be just fine for where you ride as would be a good 20W50. Your choice.

Bear

 

Since a qt of 20w-50 synthetic only costs around 9 bucks, give it a try, I tried it and I really didn't like it and went with the gear lube from Amsoil 75w-90 and I can find neutral very easily and it has been about 4,000 miles since I changed it. I was told I can go 10,000 miles on the transmission and primary if I use synthetic. Since it is shifting so smooth, I don't really want to change it out anyway. ride it like you stole it.,

 

Red Line shockproof heavy.

 

Agree with Wild Bill, 100%.

EZ[sm=bling.gif]

 

I use redline shock proof Heavy.Works great.

 

I also use Redline Shockproof Heavy. The Redline tech says it should go 20-30000 miles. Go to www.redlineoil.com it will smooth out your trans. Try the Redline MTL in your primary as well. Works well for me.

 

I use the syn 3, no problems yet.

 

Thanks forpointing me in the right directionguys. There seems to be a wealth of information on this site. Excellent Redline website KBFXDLI thanks for the link.
My next question(s) surrounds exhaust & stage 1/injector mapping etc. but I'll post that in the appropriate tech forum.

Thanks again

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