I know oil choices are based on opinions/beliefs but this should be simple enough...
I know the minimum requirements for the 08 jku is 5w-20 (not sure if conventional or synthetic). When i bought the jeep (the third party dealer) it had what i assumed was the recommended oil. When i did my first oil change at the purchasing dealer they put in 5w-30(they said it was better for winter for x,y and z reasons)... Now they are no longer in business so i dont know what oil type to use for my next change which will be this weekend.
Should i go synthetic or conventional (5w-20 or 30)??
If price is any indicator i paid 30 an oil change which is cheap since in my previous car (mercedes) it was about 85 a change.
Location: A Space Ship, in the unknown dark Galaxy!
Since you are back in a cold environment, then I would recommend synthetic, because of the better improved oil flow characteristic in cold temperatures.
As for the viscosity, I believe that Jeep recommends 5w20 for the 3.8, but 5w30 should also be acceptable.
If the manufacturer recommends 5w-20, than IMHO, that's what you should use. In extremely COLD weather, a 0w-20 wouldn't hurt, as the first number is the viscosity of the fluid when cold, and the upper number is it's viscosity when hot. Thinner oil flows better than thicker oil, and it's less work for the oil pump. You can get away with using 5w-30 or other viscosities, but for how long ??
Synthetic oil IMHO is better than conventional, but either will suffice as long as you don't go beyond the manufacturer's oil change time/mileage.
Stay away from "semi-synthetic" oil, as there is no standard for how much synthetic goes into a quart of regular oil. It could be 50/50 or 1/99.
I think the 2014 now calls for 5W20. The 2012 was 5W30. I'll use 5W30 conventional for maybe 10,000 miles and then consider switching to syn since I use syn in my 4Runner. May leave the Jeep on conventional since it is easy to change every 4K-5K. I have heard of a couple of shear-stable 5w20s but need to do some more research. Any good oil will work- conventional or synthetic...really.
2014 JKU Rubicon- all white with tan leather
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Location: Ponderosa Pine Country, where the Bears are hungry!
^^^Most 5w20 conventional oils are fairly shear-stable, but most 5w30 conventional oils are not.
Bob the oil Guy, has stated that most 5w30 conventional oils, will shear down to 5w20 after the first 1,000 miles.
This is just another reason why I like the 5w30 synthetic, which is considerably more stable.
5w synthetic for good low temperature flow, and the 30 portion for high temp protection.
It's a combination that is very hard to beat!
What is kind of comical about all of these oil threads is, when is the last time that you heard of a engine failing, because of poor oil quality? I haven't heard of, or seen any in years! So maybe that tells us, that all oils for many years, are of a high quality, and should not even be a concern........
Probably wrong place but I wondered why the search function was set up for so many hits? Usually I use it because I want to check up on a topic and don't remember where it was at. Don't need so many hits.
I just went through oil change training at my high school. If you have less than 30,000 miles on the vehicle, USE SYNTHETIC OIL. It keeps the engine ridiculously clean, and doesn't sludge up. You can also go 7,500 mi on a synthetic oil change versus 3,000 mi on conventional. Your dealer was probably just trying to sell you a more expensive oil, anything with a W in it, as in 5W-20, is suitable for use during the winter. Use the weight that your manual says to, it's been tested thoroughly by the manufacturer. If you go too thin of an oil viscosity, you start to get metal-to-metal contact. Go too thick of a viscosity, and smaller oil passageways get less flow of oil to them, again causing metal-to-metal contact, thus possibly destroying parts, or your whole engine.