power pro for spectra, p-line for mono, segaur for fluorocarbon
each of your rod and reels should have a specific application. Some are all mono (40lb mono= jig stick), some are all spectra with a fluoro leader(65lb spectra with 3-6 ft 40lb fluorocarbon=kelp cutter), and some are a little of both.
More importantly if you think your line is old you should change it. If you think your leader got kinked, nicked, or chaffed, change it. If you think your knot was tied incorrectly retie it. If you have to second guess these decisions then definitely change your line immediately and/or retie your knot.
Last year I hooked a nice yellow on fresh 40 lb. It kicked my ass, but I landed it. The guy next to me was not so lucky. He hooked a nice fish just after I landed mine. Unfortunately he lost it as his line snapped. I asked him what happened and his buddy responded for him. Apparently he had decided to be lazy the night before and just fish with old line that hadn't been replaced in over a year. That was that and he lost a nice yellow. If you're going to fish for big fish be prepared. You never know when you will hook your next big fish. IMO if your gear is in bad shape or if your line is old then you're not ready to hook into and fight a big fish. Why even try? You will be disappointed time and time again.
I have lost my share of fish, and many of them were due to equipment failure.