I would think that any motor oil with an API rating higher than
SG would do just fine. As far as deciding whether to use a
straight or winterized type, that might depend on your driving
habits and the environment in which you live. My best guess would
try 10W-30, if it thins on you, try the next highest…10W-40.
Stick with the major players and you should not have any problems.
I have always used Quaker State 10W-40 and works for me.
Just do not forget to change your oil often. Severe or normal duty
calls for changes at either 3,000 miles or three months, whichever
comes first. Some change at 2,500, just depends on your driving.
Extreme duty calls for changes at 1000 miles or one month.
If you were caught in a bad stuck and really had to rev it hard,
it would be wise to change the oil the next day. Usually after
a hard workout like that, the oil will smell like fuel. Drop the
oil as soon as you can if that happened. Use a clean pan to catch
the oil in so you can check for anything that looks abrasive or
metallic. If you did suspect possible engine damage, it would be a
good idea to stop off at your local 25 cent wandwash and use the
high pressure guns to spray off any dirt on your oilpan and filter.
That way you will not be decieved with gritty soil at the bottom
of your catchpan. Also, keep your engine running if you are going
to spray anywhere close to it. Chances are the exhaust manifolds
will get overspray and the resulting steam might stop your ignition
dead in its tracks because the cap and rotor became damp from the
steam. Usually, if the motor is running, it won’t stall as easy.
But it is not silly worrying about what type of oil you want to
use. Afterall, it’s your motor and there is nothing wrong about
"obessing" about the best protection. If your budget allows, try
using a synthetic. Keep in mind that regular motor oil is not
compatible with the synthetics, so keep an extra quart or two just
in case you might run low. Not all stores may carry synthetic oil.
If you are really serious about getting the best protection from
motor oil. When the time comes to rebuild your engine, check into
fitting a higher capacity oil pan, high volume pump and dual filters.
I am not familiar with the Chrysler aftermarket w/your Wrangler,
but getting a pan with a six-seven quart capacity seems possible.
Just make sure you measure the sump, it would be a bad move
to compromise ground clearance for a larger oil pan if you end
up taking that Wrangler offroad often.