I have a 2k 4.0L Jeep. What is the best overall oil weight to use? Best brand if there is such a thing.

 

try royal purple 10w30 or 10w40

 

I've run Castrol in everything for 12 years with zero failures. Quaker State is also made from a higher grade crude...I hear good things about synthetics, not for me as I maintain....more engines than I can count! 10 or 12.

 

10 30 is what your manual will say and what ever you use stick with it. your best off sticking with the same brand of oil every time you change your oil.

 

Depends on the primary ambient temperature. Your owners manual will confirm this.

*10-30 if the outside temperature is primarily ABOVE 60 degrees farenheit

*5-30 if the outside temperature is primarily BELOW 60 degrees farenheit

Personally, I run 10-30 down to about 45 degrees or so.....

 

I use Mobil 1 with K&N oil filter. As far as weight I use 5W30 in winter and 10W30 in summer.

 

I've used 10w30 in warm weather and 5w30 in cold weather for years, but I'm planning to switch to 5w30 year round. I don't see any advantage to the 10w30 as I read more about lubricants.