4% isnt going to make a huge difference but if you went from 8% to 20% the difference would be night and day. Again you can run 20+% oil or even 16% its just not my thing and I know most of the other nitro guys on here dont care for anything with more than 12% either. If you already got 7...
I just prefer nitro fuel with between 8-12% oil. I normally use Odonnell's which is only 8% oil so even 12 to me is a bit on the high side compared to what I'm used to but I definitely dont like anything more than 12%. You can run it just like you can run Traxxas's Top Fuel but I dont personally...
Byrons, just like Sidewinder, has 2 different formulas. They have a 12% oil and a 16% oil blends. The 12% is good, the 16% is not imo
Bryons is out of business I believe these days though
Odonnell's and Bones Brew are pretty heavy favorites around here. Odonnell is my main go to. That being said I dont think I've ran a nitro in quite awhile.
Sidewinder Race blend is fine too. The Race blend is 12% oil and the Backyard basher is 16% oil