New guy here - 99' Cherokee cracked block - had it replaced with jasper engine. Had the break in oil for 500 miles, after that my mechanic changed the oil with Rotella 15w-40 oil. I live in western NC and it is the winter - is this oil ok for low temps or can I change the oil with Mobil 1 synthetic without any ill effects - thanks

 

i dunno iv been running 20w-50 oil for a wile now. cold starts it takes a sec for the oil pressure to get up .

 

alot of people run rotella 15w40 for the zinc in the oil...and because it is thicker...im thinking about giveing it a try on my next oil change....

 

royal purple full sythetic cant go wrong

 

Would it hurt the new engine if I switch to full synthetic oil with about 1,000 miles on it? - thanks

 

will hurt your Wallet.....

 

It will only help the engine.

 

Generally 3-5K is the time to switch. The idea is to give the Oil scrapper rings time to seat....But mobile one is a good oil...I just have To many miles on it for synthetic....Also you may want to check with jasper's to see if there is any restrictions on the Type and weight of oil. Because if for some Reason a Engine failure Happened you wouldnt want them to point fingers at the oil.

 

Rotella 15w-40 is awesome stuff, i ran it in the ranger and ran it in one of my 4wheelers very good stuff, plus i get it for free from where my dad works lol.

 

rotella 15-40 is about as good as it gets for deisels, if you want to switch to synthetic thats fine to but remember you will want to run the synth. for the life of the engine.

 

i cant imagine using anything but 15w-40 i live in northern IN and it gets pretty cold here and i have never had any issues.

 

Awesome. Thanks for the replies - New to the forum and Jeeps.

 

Would it be beneficial to run diesel oil in my 4.0? Live down south, so it's hot. Maybe like a 15w-40 diesel?

 

This is an old thread and full of oil myths/misconceptions.

Read the Motor Oil link below.....then u will be have a better understanding of motor oil viscosity than most folks AND will be able to make your own educated decision about what weight oil to run. U will have a better understanding of what lubrication is and isn't.

http://www.supramania.com/aehaas/

 

How about salad's write-up?