I have an 11k camper...going up big hills/long grades I generally try not to hold the rpms past 4k (red line for the 8.1 big block is about 5k I think). 160k miles...engine is midly worked. Am I being overly cautious? I think on i70 in Colorado, I held it at 4k for like 15 minutes straight. Probably one of the more extreme examples. I'm not worried about overheating -- I'm worried about engine wear, especially the crank/rod bearings. I run 15w50 btw. I would like to push it 4500. At 4k in 2nd gear on the really big hills, I lose momentum. Perhaps at 4500 I could hold it. Idk. What do u guys think?