I run a 50-50 mix. The Hot Rod fan is $249.00 complete. You can have my old direct drive fan for free after I get my electric one on. This brings to mind,how many blades are on your fan? I have 6. You need @ least 5. The Spal is a very good fan but it gets really hot here. Even If the Spal was free but didn't cool what good would it be. Go on the internet,look up the Spal fan you have and check the deminisionsand CFM,then go to Hot Rod Air and check the deminisions on their fan. Or you can wait about 3 weeks when I install mine and I will let you know how it works,Hell I will even let you help me install it!! At the same time of the fan install I will also be putting in an A/C system, 1 wire polished 180 amp alternator,Billet pulleys and brackets, an Edlebrock Victor series Endurashine high volume water pump and a new blower motor for my heater. AHH just look at the experience you will get PLUS--I have FREE BEER!!