How did the inside of your 300ZX get soaking wet when it hasn't rained in two months? We'll give you a hint: The water is coming from the inside of your vehicle, most likely leaking from the Nissan heater core that's hiding in your dash. The Nissan heater core has its pros and cons. On one hand, since it uses hot engine coolant to provide heat for the passenger compartment, Nissan heater core doesn't use up any energy when it's operating. On the other hand, to provide that heat for the interior the Nissan heater core is stashed way up in the dashboard on the inside of your ride. Not only does that make any leakage a major problem, but it also makes the Nissan heater core notoriously hard to get to for repairs. You may have discovered that when you priced out a Nissan heater core replacement. Don't worry, though: You can do the job yourself with a good repair manual and a replacement Nissan heater core from us. Give yourself plenty of time to accomplish the work and follow the instructions step by step. Since you're using one of our premium replacement Nissan heater core units, this should be the only time you have to do the job. You can help your new Nissan heater core live a longer life by changing the coolant yearly too. Antifreeze contains corrosion inhibitors that wear out over time, so even though your coolant may still maintain its temperature resistance, the lack of corrosion protection could be eating away at your new Nissan heater core. After all, as we mentioned, Nissan heater core replacement isn't a job that you want to do twice!