You will not void the warranty by using a different fuel unless the fuel being used has less oil content than that which is being recommended by the manufacturer. If something happened to the engine and a question was asked about the brand and nitro percentage of the fuel was being used and you said Traxxas Top Fuel 20%, they would say “well, that isn’t the problem then”. Too much oil will not harm an engine, it’ll only eat glow plugs and cause sluggishness in the engine.

Another thing is it almost impossible (didn’t say it was impossible) but very, very, very difficult to get an engine “warranted”. The manufacturer virtually always says (depending on failure) that it wasn’t broken in correctly, over revved, too lean, blah, blah, blah.......all of which pointing to operators error.

From reading what you said about your temps during break-in and you saying you hadn’t touched the HSN I was taken aback. I recently broke-in my .26 myself (a few weeks ago). Just after the first tank I started leaning it out little by little and short WOT bursts were growing longer and longer to where there were really long WOT bursts. I couldn’t get heat in my engine to save my life. I was into my 9th tank before I started getting aggressive with the tune and I still couldn’t get the head temps above 200. I strapped the truck down on our chassis dyno and after the tuning was done, my HSN is approximately 1/4 from being turned all the way in. Good gawd at the power and I can run the living padooky out of it for a full tank and the head still won’t read but about 220 degrees. This is which running Traxxas 20%. If I run Trinity 25% my head temps drop to about 210-212 with the same tune. If I run Trinity 30% it’s difficult to get a head temp reading more than 200.