15W40 Heaven!
#62
JK Super Freak
#64
JK Super Freak
#65
JK Super Freak
I have the exact same oil consumption issues expressed on this thread. About a quart every couple thousand miles or so. I have almost 60k miles on it and drive like a grandma.
I am going to start adding 15 40 now when it runs low and see how things go.
Thanks for this thread it has been very informative.
I am going to start adding 15 40 now when it runs low and see how things go.
Thanks for this thread it has been very informative.
#66
JK Super Freak
Join Date: Nov 2009
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Ok, thought I'd post another update on my progress after switching to 15W40, as I just did another oil change yesterday (as I do them every 3500miles it would normally have been two in this timeframe since I made the switch however the Jeep was laid up for a few months while I was interstate for work). 6 quarts went in last time, & I drained 5.5 quarts out after 3500 miles, but in hindsight I didn't drain the filter & measure this as well so all up it appears the motor used little if any oil during this period. Also pulled the PCV tubing as well & it only had a light dusting of oil vapour in it, & wasn't dripping with oil as it was when I was running the 5W30.
Motor is still running smooth & stong and no longer pings noisily under load and is quiet and without the coarseness and ticks/rattles/knocks that it had when running on the thin oil specified by Chrysler. All in all I'm very happy with the results from running this motor with approximately the same weight of oil that it was originally designed for.
Motor is still running smooth & stong and no longer pings noisily under load and is quiet and without the coarseness and ticks/rattles/knocks that it had when running on the thin oil specified by Chrysler. All in all I'm very happy with the results from running this motor with approximately the same weight of oil that it was originally designed for.
#67
JK Freak
I drive 60+ miles on the highway each day and noticed that I was burning oil (~1000 miles I'd lose a quart) with the 5w20, made the switch to 10w30 and the oil burning has stopped!
The jeep is running better than ever and I did note a slight increase in MPG.
The jeep is running better than ever and I did note a slight increase in MPG.
#68
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.
#69
JK Freak
Join Date: Jul 2008
Location: West Jordan, UT & Prescott, AZ
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I decided to try Castrol GTX 10W-40 combined with a Purolator pure one filter. Results so far have been great, no start up rattle, no oil consumption, engine is quieter at idle.
#70
JK Junkie
It REALLY does help
I've used Pennzoil 10W30 exclusively since 1988. Nothing else. Chevy's, Buicks, Oldsmobiles and Jeeps. NO issues, no clattering, no oil consumpsion at all. Well over a million miles total on these vehicles and NO issues. I've always used Fram base filters- No issues, no drainback, no clatter, no leakage. I've advised friends to drop their synthetic oils because of usage concerns and engine noise, and in every case real improvement has been noted. It's all in ''cling'' and film thickness of the oil being used. The synthetics are simply dyno oil manipulated to ensure same-sized molecules. Sounds good, but the thin film and low cling cause your little tics and startup noises and yes, oil usage. My '95 YJ, a 4 cylinder 5 speed had 198,000 on it when I sold it, no ticks, noises or oil usage. None. My '98 Olds had 162,000 when I sold it, no issues. My '01 Silverado had 125,000 and no issues. My '06 Impala has 130,000 now and no issues. None. I've used 10W30 in my JK (75,000) since almost new, no usage, no ticks. None. I change myself every 3000 or so. This is my real-world experience. Best of luck!
Last edited by TINMAN080; 08-12-2012 at 06:28 AM.