stick with the 88 it is your motors design temperature, and the rad and fan can easily dissipate the heat even towing slow uphill but it is important that when the gauge starts to climb that you can hear the roar of the fan as it cuts in, if no roar and temp continues to climb, then stop and run engine at fast idle to cool it down, this would indicate the viscous fan has failed, I know of know other way to test it Rick