I've read thread after thread about deltas and figured that if your spread is more than 10-15 degrees while running 60mph on the flats, it's probably clogged or at least on its way out. I took my truck out for a drive a couple of weekends ago and my deltas were 13-16 degrees, so I figured I was a bit clogged. No big deal, kind of expected, start saving money and planning to swap coolant then cooler etc.
However, over the last couple of days I put about 350 miles on my truck in different terrain with a trailer, loaded and unloaded, and my deltas were... 13-16 degrees on the flats at 60 pulling this trailer:
Not a huge load by any means, but I expected it to spread the deltas out. There's not much flat ground around here, so I was constantly going up hills and down hills. When going up a grade at 60mph, ECT would be ~210 when EOT was 222, then the hurricane force fan would kick on and my ECT would drop to 198 within 45 seconds. EOT wouldn't drop nearly as fast, so at times I would have a 20+ degree delta. I never saw the EOT go above 222, and when I was in city traffic ECT would be 190 while EOT was 196 or so.
Anyway, I guess I'm a little confused. Maybe I'm not as clogged as I thought I was. If not, it makes me a little more leery of doing the coolant flush/swap right off. I was planning on waiting until the cooler was showing signs of plugging, then completely clogging it with the flush just before replacing it (plan for the worst, hope for the best kinda thing).
What do you guys think the deltas are telling me?