I will be trading my current truck for a 2000 PSD F350 crew cab srw 2wd auto. The drive train is stock. This truck was my father inlaws he got it to pull a 36ft 5er. The truck has been trouble free and has a 100k on the clock. They took one long cross country trip in it pulling the trailer. Then maybe a few more local trips no more than a 100 miles total. With that being said I would really like some help as I am new to diesels. I do plan to use the truck to pull the 5er that came in the deal. The 5er wieghs about 12k loaded. First I will change the oil and rear end diff. Next I will do the coolant. The first mod I want to do is a larger tranny cooler. So here are some questions. What oil is Delo 400 le ok ? Coolant wise what do I need to get ? I have read on here about a 6.0l tranny cooler. I have not been able to find one yet. Thanks for your help.