You mean higher flash point. A lower flash point would be more prone to dieseling. That's not here or there. I knew what you meant. I just wanted to point that out. Dieseling can be eliminated by using Teflon based greases like Krytox or Ultimox. They're non petroleum based and technically shouldn't diesel at all. If you use too much it does smoke somehow. It may be vapor rather than smoke.
I use both petroleum based lubes and Krytox in my builds. Never in the same gun. Krytox is expensive so I save it for guns with compromised compression tubes. Those are compression tubes that have scoring in the seal travel that's too deep to hone out. Krytox is supposed to be more temperature stable but I've never noticed it being any better. I don't shoot when it's 20 degrees out either. You lose 10 fps going from petroleum based lubes to Krytox. That's in the best built, tightest sealing piston guns. Even those diesel a little bit with petroleum lubes. It's just not detectable. You'll lose more velocity with Krytox if the gun is dieseling noticeably.
Krytox guns also seem to get dry and sticky before guns lubed with a good petroleum based lube. Therefore I pretty much save it for guns that have sealing issues.
If your 97 is still dieseling after 5K shots and you haven't been adding lube to it, I'd have to think the seal was probably damaged on installation or they used a ton of lube. A 97 has a machined sliding compression tube so they're not as prone to damage or concentricity issues as break barrels. Either way it ain't right. Dieseling can cause accuracy problems and point of impact shift. Excessive dieseling can be tough on the spring too. Not as bad as detonation which is that loud crack you get when there's too much lube in front of the piston seal or the rifle is dry fired. A single detonation can cut spring life in half.
Hope this helps.
I think you have my number, feel free to call me if you have any questions.
Ron