Pages 82-83 are valve lash adjustments for the V6 engine. They are simply explaining multi-grade engine oils and leaving the decision to the end user. Which makes sense. I guess this was a time before manufacturers would void warranties due to "use of improper oil viscosity".

This is the actual quote from the 1989 manual, page 15.

"Multi-viscosity oils are designed to have characteristics of both light and heavy oils and are available in a number of weights from 5W-20 to 20W-50."

The fact is, this engine design is very low stress, low RPM, standard oil clearances, low friction. Break-in procedure aside, this engine in a daily driver scenario, will run just fine regardless of the engine oil.

That is a hilarious oil thread. The guy copied and pasted all kinds of material and still doesn't have a minute understanding engine oil. That whole thread doesn't contain a single mention of rod and main oil clearance. You guys do understand that rod and main clearance is the prime determining factor for engine oil viscosity right? The guy is fixated on "tractor engines". Tractor engines are generally much more complicated than passenger vehicle gas engines. They require a different fuel, higher cylinder pressure, heck they don't even have spark plugs. Neanderthals, with genetically limited mental capacity, are the folks who compare the Jeep/AMC straight 6 to a John Deere Diesel.

 

Clearly you don't know what you are talking about. Just how does a gasoline tractor engine run without spark plugs? They also use the same fuel and aren't that complicated at all.The jeep 4.0 can use 20w50 no problem. It is an entirely different engine and design than a 4.7 POS.

 

Bro, who the hell runs a gas tractor. When you think "tractor engine", your brain goes to GAS!@? Neanderthal....Tractor engines run sleeves with O-rings and high pressure pumps, giant injectors, diesel fuel, turbochargers, a lot of the inline 6's are 24 valve.

Nobody said that it couldn't. Pay attention or go back to Pangaea...

 

Yes we have had several gas tractors, Ford, Massey Ferguson, and International Harvester just to name a few brands. They are very common, also when you say tractor engine in reference to a 4.0 it is pretty common sense that you are referring to a gasoline engine since the 4.0 runs on gas.

 

The AMC straight 6 was NEVER a tractor engine!! https://en.wikipedia.org/wiki/AMC_straight-6_engine

That's the kind of crap the British did.

 

280k and I run the same. I have a strange tap sound on the driver side of the engine but I haven't narrowed it down to lifters or possibly just an exhaust leak in the header. Castrol 10w30 does the trick for me, like you said it's all about regular maintenance
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