How long to wait before rebuilding a strait 6 on a 94?

I agree. I bought mine and oil was changed every 3K and the clock is at 190800 miles. I am now using Mobil1 synth and no leaking. The seals are good because of the frequent oil changes from the PO.

I just turned 238,000 miles on my 91YJ. I've changed oil every 3000 miles since new. Still runs incredibly strong.

Have someone tail you down the road and see if a puff of Blue Smoke exits the tail pipe when you shift. Or look for smoke on a cold day initial startup. Sometimes tells what the Piston rings or valves are up too.

I redid the 258 in my 87 yj at 220,000, only reason i had to do it then, was i was an idiot, broke the choke lever and wound up running it excessively rich for about 4k before i found the problem, by then needless to say the rings were pretty much toast..

Esty wrote:

I asked the PO about the frequency of the oil changes. I checked the dip stick and CCV. The CCV was clogged but not bad so I think he never had that replaced since the frequent changes slowed down that issue. I replaced the CCV and intake hosing to the air filter and that really helped.

wait until you sink it in a mudhole without a snorkel, that's a sure sign you need a rebuild

really though, unless you've got drivability or emissions problems, don't worry about it. (if it ain't broke, don't fix it)