My wife just bought a new Toyota and looking through the maintenance schedule, Toyota says (recommends) to add their "Toyota EFI Tank Additive" every 5000 miles. Luckily, it only applies for Hawaii and Puerto Rico, so it must be hot(ter) climate related. Is this normal for Toyotas in those climates ? This is the first automaker that I've seen that says add any additive at all, whether it's fuel or oil related.