15W40 Heaven!
08-12-2012, 08:16 AM
#71
I just want to add some basics here. If your crankcase vent(PVC) is moving lots of oil your rings could be worn, or your oil is so thin it's bypassing the oil control ring.
The first number, 0, 5, 10,15 or 20 is the cold thickness of the oil. You really want the lowest number. The lower the number the faster the oil reaches the lifters and bearings during start up. Ironically you'll have a louder engine with a thinner weight on a cold engine, but it's lubed and if you don't beat on a cold engine your fine.
The upper number, 20, 30, 40 and 50 of course is the hot thickness. A 20 will make a louder(ticky) motor that has more power but it could suffer more wear as the light weight oil has a low shear tolerance. The heavier weight will sap power but run quieter and last longer. Just remember, the hotter it is outside or under your hood like while towing, the less protected you are. The thinner oil will turn into mist easer as mentioned, this sends oil into the PCV, which in turn is burned again in the combustion chamber. If enough oil is present detonation will occur and the ECM will pull timing/less power.
A couple of years ago oil switched to low/no phosphorus and zinc. Older engines need those to resist wear. The Ph and Zi was especially important to flat tappet engines like the 4.0L. The 3.8L is a roller cam but it's possible the rings aren't new oil friendly. I believe the change occurred during the API change to SM from SL. On the other hand most diesels on the road are flat tappet. Diesel oil still has the Ph and Zi content to protect your engine. Also speed shops like summit racing will sell Ph/Zi additive bottles or "offroad" use oil in regular and synthetic.
It's also been proven many times that synthetic starts thinner and holds its thickness better when hot, even really hot compared to conventional.
I'd recommend 5w30 diesel synthetic or 5w40 which is easier to find in some places to any 3.8L owner, or royal purple 5w30 offroad which is what I use since summit is close.
The first number, 0, 5, 10,15 or 20 is the cold thickness of the oil. You really want the lowest number. The lower the number the faster the oil reaches the lifters and bearings during start up. Ironically you'll have a louder engine with a thinner weight on a cold engine, but it's lubed and if you don't beat on a cold engine your fine.
The upper number, 20, 30, 40 and 50 of course is the hot thickness. A 20 will make a louder(ticky) motor that has more power but it could suffer more wear as the light weight oil has a low shear tolerance. The heavier weight will sap power but run quieter and last longer. Just remember, the hotter it is outside or under your hood like while towing, the less protected you are. The thinner oil will turn into mist easer as mentioned, this sends oil into the PCV, which in turn is burned again in the combustion chamber. If enough oil is present detonation will occur and the ECM will pull timing/less power.
A couple of years ago oil switched to low/no phosphorus and zinc. Older engines need those to resist wear. The Ph and Zi was especially important to flat tappet engines like the 4.0L. The 3.8L is a roller cam but it's possible the rings aren't new oil friendly. I believe the change occurred during the API change to SM from SL. On the other hand most diesels on the road are flat tappet. Diesel oil still has the Ph and Zi content to protect your engine. Also speed shops like summit racing will sell Ph/Zi additive bottles or "offroad" use oil in regular and synthetic.
It's also been proven many times that synthetic starts thinner and holds its thickness better when hot, even really hot compared to conventional.
I'd recommend 5w30 diesel synthetic or 5w40 which is easier to find in some places to any 3.8L owner, or royal purple 5w30 offroad which is what I use since summit is close.
The first has to do with the viscocity characteristics of the oil. The second winter number is cold start viscocity. So the first number is how it flows at opperating temperature, the second number is how it flows cold.
I know a few people who have changed to using diesel synthetic on their older vehicles. Something about it seems bad I just can't put my fingers on it.
08-12-2012, 12:42 PM
#73
JK Junkie
Many guys change their oil initially at 2-3000 miles. That way if any machining debris is present it gets flushed early. Then set up an oil change schedule you are comfortable with.
08-12-2012, 01:06 PM
#74
JK Enthusiast
Join Date: Aug 2011
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The first has to do with the viscocity characteristics of the oil. The second winter number is cold start viscocity. So the first number is how it flows at opperating temperature, the second number is how it flows cold.
I know a few people who have changed to using diesel synthetic on their older vehicles. Something about it seems bad I just can't put my fingers on it.
I know a few people who have changed to using diesel synthetic on their older vehicles. Something about it seems bad I just can't put my fingers on it.
10W-30 designates a common multi-grade oil. Historically, the first number associated with the W (again 'W' is for Winter, not Weight) is not rated at any single temperature. The "10W" means that this oil can be pumped by your engine as well as a single-grade SAE 10 oil can be pumped. The second number, 30, means that the viscosity of this multi-grade oil at 100°C (212°F) operating temperature corresponds to the viscosity of a single-grade 30 oil at same temperature.
08-13-2012, 04:08 AM
#76
JK Freak
My JK has terrible start-up rattle. I'm getting the Mopar filters as the dealership does the change. Do you guys think there is anything correlated with a cheap filter letting the oil seep back into the pan, or the weight of the oil used?
I know the dealership is putting in the stock weight and have no problem topping off with 10-30 after half a quart is burned off.
I know the dealership is putting in the stock weight and have no problem topping off with 10-30 after half a quart is burned off.
08-27-2012, 06:46 PM
#77
JK Junkie
My JK has terrible start-up rattle. I'm getting the Mopar filters as the dealership does the change. Do you guys think there is anything correlated with a cheap filter letting the oil seep back into the pan, or the weight of the oil used?
I know the dealership is putting in the stock weight and have no problem topping off with 10-30 after half a quart is burned off.
I know the dealership is putting in the stock weight and have no problem topping off with 10-30 after half a quart is burned off.
08-28-2012, 06:42 PM
#79
JK Junkie
Join Date: Oct 2007
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5w-30
10w-30
10w-40
15w-40
I have a 2012 as well and did my first oil change at 1k miles. Since then I have driven a total of 2600 miles and The Jeep has no loss of oil. I check the oil level every week....
