What Fork Oil for my Panhead Frontend, AND WHY?

[JamLazyAss]

What weight (or brand if not HD) fork oil should be used for a Panhead frontend, AND WHY?
The local dealership carries two weights, but which is preferred and why?
This has always been one of lifes great mysteries to me 
Thanks...

[dave_9113]

Save your money.  Straight 30wt, but that's just me. 

dave

[ModelABob]

Non-detergent 30 wt. is what I always use to use.  I'd be lucky it neither one of the tubes didn't
start leaking anyway.

AMF/Ride Safe

[PC_Hater]

As I don't know what fork oil Harley specified I will believe the previous posters and say that 30weight is a good place to start.
If that is hard to get then 20W50 engine oil will do nicely.
Bel-Ray and probably others do a proper 30W fork oil - that will work even better.
Why such a thick oil? To give reasonable damping in a crude fork design that now has 50 years or more of wear in it!
You might prefer a thinner fork oil. That will reduce damping and feel softer with more dive under braking - if you can get the brakes working well enough that is! Your forks might be so worn that using 40W or 50W engine oil is the way to go, especially in Arizona in the summer.
Oil is oil is oil but the oils that are specifically fork oils have anti-foaming agents and chemicals to make your fork oil seals work better. Important on a modern long travel dirt bike suspension, less so on tired old forks. Except possibly the  oil seal improvers?