10w-30 synthetic here, I noticed an immediate improvement in gas mileage when I started using it when the engine had about 70k miles on her, now up to 190k and engine still runs great. I take several weekend trips to the mountains during the winter so extreme cold starts are common for meh. Despite the comments above, I can get 5 quarts of the stuff for about $6 more than non-synthetic @ WalMart, that's really not that much more and I feel more comfortable letting her go 5-6k between oil changes instead of 3-4k like I used to do, so it is actually cheaper. I hear you can do 8k+ in a 12 month period if you really want to live on the edge.
I run Chevron Delo 15W-40 oil in my 4.0. Can't beat 1300 ppm of Zinc and 1200 ppm of Phosphorus for $10 a gallon. That and a Mobil One oil filter.
I've tired several oils in my 4.0 and the Delo by far gives the lowest levels of metals in the oil on a used oil analysis.
In memory of Samantha Sue 1998 to Dec-16-10 at 2:15PM. She may have had 4 legs and a tail but she was the best friend I ever had and helped me through some really tough times. I hope to see her again one day.
I live in Michigan so it's Valvoline 10w-30 dino in the summer and Valvoline 5w-30 dino in the winter with STP S8A oil filter for extended capacity on all three of my 4.0L's. I also change the filter with every oil change.
99 xj - 252,500 miles (every 5,000)
03 wj - 176,000 miles (every 5,000-6,000)
97 tj - 119,000 miles (every 3,000)
Like FL 4.0L I also purchase the Valvoline at Wal-mart. A 5 qt. jug there is the same price as a 4 qt. jug at AutoZone/Pep Boys/etc.
Personally, I don't have any problems with Penzoil. People debate the particulars and the minutiae of oil on a constant basis...and for me, the bottom line is this: they all work well when used properly. I've run Penzoil before and never noticed any problems from it.
I can't say much about the 2.5, but the 4.0 was designed in an era when our cheapest, most crap-tastic oils would have been considered state of the art. It's a very tolerant beast...as are most engines. Thus, I believe that dino oil, a good filter (I've even used Fram and never killed an engine...my stars!), and changing both regularly will serve you well.
If it's worth doing, then it's worth overdoing.
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What do you guys think about penzoil 10W 30? Ive been using that for the past couple years. I like it but i never hear anyone use it.
Pennzoil earned a bad reputation for sludge years ago so not many have forgotten it. But that problem went away something like 15 years ago when they went to their PureBase product that dropped the use of paraffin that was the cause of the previous sludge problem. With that long-ago change to their base, their engine oil has been as good as anyone's for many years now.
I'd run Pennzoil without a second thought if I couldn't buy Valvoline any more.
that makes me feel a lot better Jerry!! thanks!! I plan on trying out Valvoline during my next oil change to see how much of a difference it is. I have also heard good reviews on the Napa Gold Oil filters. Do you have any experience with them?
I have also heard good reviews on the Napa Gold Oil filters. Do you have any experience with them?
I use them and love them. They're just a Wix filter, which is a very good filter. My LJ is very happy with Valvoline 10W-30 Dino and the Napa gold filter. I also ran that oil and filter on my TJ before it got totaled and it gave me 180k trouble free miles.
1990 YJ-The wheeler
2015 JK- The DD
Swapping from one good major brand of engine oil to another good major brand of engine oil isn't going to produce results you will notice. Those that claim they immediately noticed better mpg, power, etc. by changing to some particular brand or type of motor oil are just victims of the Placebo Effect.
I don't know for sure who makes NAPA oil filters but I believe they are made for NAPA by Wix which is a very good brand of oil filter. Personally, I stick with either Purolator PureOne or AC-Delco Duraguard oil filters but Wix is among the "good" brands that are good to use.