Who uses transmission fluid in there primary case and how effective do you find it either gm or ford I have used it for years on my Blockhead but about to change fluids on my Twinkie and thought of finding out, and while at it what gearbox oil do you all use ???

thanks smut

I have a 99 Twin Cam and use Mobil 1 full synthetic 20W50 in everything.

Go the Redline in the tranny.....

+1 on the Redline in the tranny

Nulon Full Synthetic Trans fluid in the primary.
Nulon Full Synthetic 75-90 Gearbox.
Will do all 3 oils again in about 1500 kms. Probably will try a 80-140 in trannie next time. Noticed a big difference when I changed from a 20-50 to the 75-90 in the trannie. A couple guys are using the 80-140 and I figure I will give it a try. I use full synthetic in all holes as they handle higher temperatures better than mineral.

I don't mean to hijack the thread;however, I have question on this topic. I did the oils on the fatty before the snowy ride. 20-50 in engine and primary and REDLINE HEAVY SHOCKPROOF in tranny. 2000ks later and the gearbox is as clunky as ever!
Prior to the ride I put in SE heavy clutch spring. Any ideas on why the tranny might be so noisy (bigger 1st gear clunk etc)?

Cheers. Bucky

When I tried type f a few years ago I didn't like it the primary /chain noise was louder now just run 30w engine oil
Or if I feel like lashing out belray primary if have it on the shelf

Or smell it!

thanks guys has given me some good ideas

smut

well I went to atf III and i'm not happy, more clunky when changing than it was and now leaks so going to something I little harder I think

hard to get a seal with atf in primary, I have used it but only when I didn't have something else handy, Nulon 75/90 primary, formula X in tranny, works for me,

HD Syn3 in all holes

it's a 01 heritage springer injected

I've gone ATF in the primary. Only done about 2,000klms on it since but no problems with noise or leaking. I've been convinced (by the chatter on here) to try Nulon in the gearbox now.

I have previously posted on engine and gear oils and compensator issues. Just thought I would update where I am with them on this thread as it is related. I have a 2007 96 cube Road King. Have had it about 18 months. It only Had 4,500 Km's on it when I Bought it in 2015. Changed everything about 7,000Km's. Decided to go qwith others recommendations rather than the standard 20/50 in all the holes. Used HD 20/50 Full Synthetic in engine; 75/90 Nulon full synthetic in Trannie and ATF in Primary. After about 2000Kms my compensator started making noise. Again; not saying the ATF was the culprit but I had noise after 2000KMs. Plenty of others had recommended ATF and a fair few others questioned the ability of ATF to protect the Compensator. I'm with the latter guys now. I understand the compensator more now and believe it needs higher viscosity lubricating than ATF. Sorta verified by the bikes noise with 2000Kms riding. I changed everything again at 11000 KMs and have 2000 Kms on the bike since. Im now running Penrite 20/60 Racing in the Motor and in the Primary. Im running Nulon 75/140 in the transmission and for the time being noone could convince me to change from this. I should say; when I made these oil changes I also pulled the primary cover to check the Compensator bolt torque in case that was my noise. I didnt pull the bolt out and redo the Loctite as suggested but I used a torque wrench to ensure it was at least 150 foot pounds. Some may say I didnt do it right but it would have been extra work to pull it and I had my verification it was tight and hoped my new oil choice would quiet the noise down. The primary noise has quieted considerably since the change. I was originally happy with changing to gear oil the first change but going up to the 75/140 was even better and am happy with that decision as well. The reviews on the Penrite are good so Im confident the engine and primary are protected and I can hear the difference in the trannie with the high viscosity gear oil. The bonus of using these two brand of oils is that they are both Australian Companies. Makes it all the better. Just my Opinion. Dont pretend to be an expert or anything.

I have always used the racing 20w60 in the engine and primary however I recently changed to penrite hpr5 in the primary and it is much smoother selecting 1st gear, especially when cold.

I havnt looked at it for about 20000 k when I upgraded the clutch.
It has a se comp which must be standard on the 103
All seems good still.
Just installed target tune, so will try and give review soon.
Cheers

Have done 60000k using penrite and wouldnt use anything else

Hey Ando and Drac. I have owned a few metrics including a couple early Goldwings which were smooth as a babys ass and this is my 4th Harley. The previous Harleys were pre 1977 and dont really compare to a twincam of today. I have never switched an oil in a vehicle and noticed such a difference like this before. With the Penrite racing; after oil pressure has built up the twin cam is as quiet and smooth as any of the Metrics I have owned. My calibrated 56 year old shitty hearing tells me its quieter at all temperatures than before the change. I know it sounds like BS but it sure feels right. The difference in the primary and compensator noise is even greater. Glad I switched backfrom the ATF to a multi grade. Id be willing to listen if someone could convince me the BelRay or Redlines in the primary were significantly better but Im pretty content buying 5 litres of Penrite for the 2 holes after what I have experienced. Im curious Drac why you went for the HPR5 in the Primary ?? My thoughts were with the heat these Twin Cams generate id rather go heavier. Not debating just curious on your choice. Cheers 

There seems to be a lot of people out there using atf and some clutch manufacturers recommend it.
Most using it say it makes smoother shifting, especially selecting 1st gear when cold.
I thought it had to be a viscosity thing because with the 20w60, if I gave it a quick rev, it would then shift into gear without the clunk.
That got me thinking that it had to be a viscosity thing.
I also read somewhere that thinner oil should make the plates release easier and not really feeling comfortable using atf because of possible compensator noise or issues, I decided to look at thinner engine oils in the Penrite range.
I went with the hpr 5 because it was the lightest full synthetic which was suitable for wet clutches.
Pull the clutch cold, wait a few seconds and drops into 1st with no clunk.
Cheers