It will be next to impossible for us to help you decide when we don’t have all the details about your budget, uses\wants for a Jeep, and most importantly, a clear understanding of your new Jeep’s condition. If you like your new Jeep, it may just be time for a tune up and some maintenance items. Even with it’s age, I would not use heavier oils than what is called for by the manufacturer in the diffs, engine, or trans, especially in cold Winters. If you drive it in cold conditions, perhaps look into synthetic 10W30 motor oil since it will flow better at startup to prevent wear. In extreme cold, 5W30 synthetic is recommended by Jeep. Otherwise, 10W30 conventional oil is fine in normal conditions.
As
@Westtown Willy suggested, if you have a pristine TJ frame in Western PA, it probably isn’t a good idea to drive it on salt roads. If you have to drive on salted roads, look into doing the following:
1) Frame cleaning inside and out (do it on a hot day\week and allow it to dry in the heat for a few days)
2) Surface rust removal (as necessary using a wire wheel)
3) Rust reformer (if necessary over select spots if rust persists in areas where it is hard or impossible to completely remove by sanding). This encapsulates it and turns it into a paintable surface.
4) Paint over any bare metal frame or suspension part or areas where rust reformer was used. I go with high temp, rust and oil resistant paint. Satin or flat black. Satin will offer a bit better durability most of the time.
5) Finally, apply Fluid Film inside and outside the frame with a spraying device. Apply Fluid Film over the entire undercarriage, just not on brakes, exhaust or engine. I would recommend FF over products that don’t easily come off if you need them to. If really serious about frame preservation, perhaps look at some of the popular internal frame coating products as well, but do this before applying the fluid film, and still apply the FF afterwards on the outside of the frame.
6) Lightly rinse your undercarriage during the Winter when using FF. Don’t use the full pressure all the time or you will remove some of the protective coat.
(Review and repeat these steps each year. Some years only 1 and 5 need to be repeated before Winter comes.)
Many of us have been in the position of owning a TJ and then finding themselves wanting a JK or JL. I started with an 05 TJ when I got the Jeep bug. I kept the TJ and then bought a used 2016 JK as a daily\Winter driver so I can keep the TJ pristine. They are different animals indeed. The TJ is a classic, the best Wrangler ever built, most will say. The JK (or JL) will be a better choice if you spend a lot of time on the highway and like to take long trips. It will be more comfortable for that. Also a 4 door JK or JL will ride even better on the highway due to their even longer wheel base. For the older TJ generation, the LJ model with the longer wheelbase typically makes for the most comfortable highway runner.
