I bought my jeep with 81,000 miles on it and it's time for the first oil change. Im thinking synthetic. But since I don't know what was used for the first 80k is it ok to make the change? Also what weight? Im assuming 10w-40.
p.s. Not looking for opinions. Looking for a solid answer.
the oil cap says 10w30 and all the 4.0 jeeps that come through the shop use 10w30.
honestly, i don't think you really need synthethic. just change the oil regularly and you'll be fine. people on here said not to switch to synthetic if you've been using standard oil but a lot of people do it.
Well first of all, do you know if its ever had synthetic before? If it hasn't don't use it due to it having higher mileage on it. Putting synthetic in vehicles with higher mileage has been known to cause engine issues. Im almost certain theres a thread on here talking about it. If I can find it i'll post it for you. I actaully just changed my oil at 81k also and I used mopar oil and filter 10w-30. Im all about OEM when it comes to fluid maintance. Your probably going to get opionions no matter what.
Synthetic oil is fine in your Jeep. It will not harm the engine or seals in any way. Synthetic oil is "better" than dino oils in most respects, but if you change your oil every 3,000 miles, you probably don't need to use synthetic.
Here is a link to the Amsoil site, which discusses oil myths in general. It should answer your questions about the suitabiliy of synthetic in you Jeep:
One of the issues we have with our "old fashion" inline 6 however, is the fact we have a flat tappet camshaft. Most if not all newly designed engines run roller cams for reduced friction and longer life. But due to the flat tappet design, we have a high pressure friction point between the cam and lifters. The newest API oil rating may not protect against high wear rates in this are. One way to ensure your engine is protected in this area is to run an oil with an ACEA rating such as:
"At what point, then, is the approach of danger to be expected? I answer, if it ever reach us it must spring up amongst us. It cannot come from abroad. If destruction be our lot, we must ourselves be its author and finisher."
Just check your dipstick, after you do your oil change. If it is low, you know you need another quart. By the way, using a quality oil is what it's all about, and changing it, every 3k miles. I personally like using Castrol, 10w-30. It is a great oil.
I use it in my YJ, with the 350 Chevy engine, and the 04 Rubicon.
If you were wanting or considering a syn, you can actually get a syn blend which is still part traditional. I've done that on my last 2 TJ's I bought used. On the first 3 oil changes I used the syn blend and then moved to the full synthetic on the 4th.
And yes, 6 qts.
04 Sahara, with a lift, some stuff, and a few things, on some 33's, blah, blah, blah.
A perpetual work in progress. Too much to list, not nearly enough to matter.
My RigRater Score: 387RRv1.0 with a BOA of 18.92 (and just how exactly is this going to help me over that big arse rock?) http://www.myjeepsite.com/nregas1 Always do sober what you said you'd do drunk. That will teach you to keep your mouth shut.
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If you go Mobil-1 just pick up a few of the 5 quart containers at walmart for $25, green cap, 10W30 and a 6 pack.
Without going into details I've switched from Mobil-1 to Royal Purple and I've been a Mobil-1 user for over 15 years. I don't like the formulation in the current Mobil as it's made for the newer engines and has had several additives taken out as have all of the newer, since 2004, oils for increased mileage and additives to increase the life of the cat converter.