I just changed all the fluids in my 97 FLHT (SE heads,ignition,Comp cam 3020,Ness big sucker,Samaon slip-ons).In the crankcase I used Castrol Syntek 20W50,Trans- Royal Purple Severe Gear 75W140, primary side Valvoline 20W50 Dino motorcycle oil. Anyone have any thoughts on this combination?

 

Those are all good oils....not what I prefer to use....but good oils none the less. My only concern would be availability. Harley notes in my 09 owner's manual what I've known for quite some time...and many folks overlook.
The additive packages in different brands will vary slightly. Sometimes, even when it's two different brands of really good oil, the additive packages won't mix well, and can actually form sludge. So, The most important thing you can do (IMHO) is to stick to the same brand of a good oil. All of those brands you mentioned are great. However, that is quite a variance to deal with every time you go buy oil for a service. Most folks stick to the same brand for all 3 holes. I personally use mobil1 20w50, except in the tranny I use mobil1 75w90.
-clutch-

 

Nothing against Castrol Syntec, but I would go with a full synthetic. I use Mobil1 15-50 automotive synthetic as do many guys here.

I want to add to this reply without editing my original post above, that I was thinking of Castrols Synthetic Blend which is not a full synthetic. I apologize for my misinformation and confusion.

 

I thought Castrol Syntek is full synthetic.

 

That combo sounds good to me. I use Mobil1 v-twin 20w50 in the enigine, And mobil1 gear oil 75w90 in the primary and mobil1 75w140 in the trans.

 

You are correct, that is my mistake. I don't know what I was thinking, I should have known better as I use Castrol Syntec in my vehicles.

My mind was thinking Castrols Synthetic Blend and my fingers were not.

 

Amsoil syn 20w50 in the crank and primary and 75w140 syn in the tranny. Keeps everything running cooler, longer.

 

What he said!

 

Amsoil 20w 50 motor ,redline in tranny.

 

+1 on that... But what you have will be fine too.