Good Flux?
 

Can anyone recommend a good solder flux please? Preferably a gel or paste type. Also, has anyone tried Novak's silver solder?

I use the radio shack brand....seems to work fine

Same here. They work good.

I haven't used Novak's solder, but if it's like Deans which I do use, it won't need flux. I use only Deans solder and have never needed flux - handles a123s (dewalt pacs) and anything else I've ever worked on.

I usually use Deans too, but Tower told me it has been discontinued due to the lead in the Proflux. I found a flux gel made specifically for electronics. The guys at my flying field recommend it highly for high current RC soldering:
http://www.ccis.com/home/hn/index_files/Page2.htm

I bought a used Emaxx and the reason I started using deans was that every connection on the Emaxx looked corroded. I asked the prev owner about that and he assured me he was not using acid core solder, but a good resin core solder. I went ahead and redid every joint using deans and saw an immediate improvement - run cooler and ran longer. I have never had anything that even begins to look like corrosion start on a conn I've used deans on.

I'm sorry to hear that they've discontinued it. I wonder just how much miniscule lead exposure the enviro's are saving us from this time? Glad I stocked up - at least it will be a few years before I need to get more.

Radio Shack soldier and paste works well

they have the Deans solder at this link

http://leeulingermodels.com/Results.asp?keywords=deans

I tried the H&N Supersafe Superior No. 30 flux gel and it is fantastic! Just beautiful solder flow with Novaks silver racing solder. I found my Dean's replacement!