I'm buying a new 09 suburban but it does not have the trailer hd package (engine and tranny oil coolers). I do A LOT of long distance towing and I will need that option. Is there anything else included in that package? I can have the dealer install both of those items. The dealer states that the engine oil cooler is pointless but the tranny oil cooler is obviously needed bc I tow a lot. Is this true? Do I not need to waste my money on the engine oil cooler?