I wish to know which brand and size automatic transmission cooler is best for a '98 Maxima. I was given a Hayden 404 Heavy Duty model recently, however I've reservations about the size.

My guess is that such a large cooler is unnecessary and may even cause the gears to feel as if they're slipping before full warm-up.

Any advice on the topic is appreciated.

The 404 is a good size, it's the same one used in the write-up.

For the B&M Hi-Tek SuperCooler, either the #70268 or #70264.

Can anyone explain the downside, if any, to using a cooler that is on the large side?

I want to preserve the tranny, AND keep it from feeling like it's slipping when the temperature is low.

before the car is fully warmed up it might shift hard. But just make sure you don't have any crimps in your lines, because your tranny will overheat and die on you. And make sure you add enough fluid to make up for the added volume of the cooler.

The B&M Cooler has a nice feature, it has a thermostatically controlled bypass valve that bypasses the cooler when the oil is cold. Amsoil has published some interesting info on their Synthetic ATF reducing operation temperatures by up to 50 F. I chose not to install an oil cooler but to install AMSOIL ATF after flushing. It made a big difference in tranny noise and operation.