I just started pulling a 29' 5th wheel and my EOT and ECT deltas are 15-18 degrees on average. I installed a coolant filter and switched to Zerex ELC in the last two years. Engine has 157K miles. I'm pretty sure my oil cooler needs to be replaced. Is this the time do to an EGR delete as well ? Should I do a delete ? Will I have to do a tune to get the computer from throwing a code ?