I do a little towing. A utility trailer with things for my college boy. About 200 miles round trip 2 times per year, maybe a little around town stuff in between. Our local auto part store only had the Royal Purple. 1, 75-90 and 2, 75-140. So I got them for the change. The question, is it a big deal to put the 75-140 even if you're not doing much towing. Any negatives? Thanks

 

I should not harm anything, its just a bit thicker.

I would use mobil 1 or Redline before I used Royal Purple though. Not sure why they add the purple dye to it, but that what they do.

 

There is one potential negative to using the heavier multi-weight: in cold weather, your JK's e-locker (if so equipped) will sometimes proves finicky with it.

I prefer Mobil 1 75W-90 front and rear. It's less costly than Royal Purple and has a very solid reputation.

 

No locker but my store only had Royal Purple, rest is Valvoline syn Blend. Thanks for the response.

 

Are you going to keep the hitch on the jeep? If you want to be able to tow any time you want, then I say to use the gear oil that the BOOK recomends. How much does sucerity cost?

 

I have a permanent hitch. I was just wondering if there are any issues with running a higher number if most of the time I don't tow. If the worse is thicker in colder (I drive at least 1/2 hour to work). I guess I really don't understand how the numbers work where it would be a problem with using it all the time. I would rather be safe then sorry. I plan on keeping it forever.

 

Like Mobil 1, Royal Purple and Valvoline Syn Blend meet the API GL-5 requirement, so you're OK there. As for the 75/90 or 75/140, you should be OK there also if you use the 75/140, even throughout the winter, unless you're in an area where the temperature reaches below 32* for long periods. The lower number is the viscosity of the oil in cold temperature, and the 140 is the viscosity in hot temperatures. Most likely a rating of 32*-212*. When towing, in summer months, the rear differentail can reach temperatures of 300* or more. That is why the owners manual recommends the 75/140.
With that in mind, however, as was posted by a few, in colder temperatures the 140 can be a bit thick. Seeing that the gears are lubricated by splash, the film would be a bit harder to maintain to start, however once warmed there should be no problem maintaining the lubrication film on the gears.
I run Mobil 1 75/140 in the rear here in SE Pa, and have encountered no problems during the winter months.

 

Thanks Lorrel.That's what i was looking for. We do get the cold temps and I guess If I just take it easy a few minutes it should warm up fine. It's chicago, we do get stretches of under 32. go figure.