rotella is good oil too. i used it for the break in period on my stroker and might go back to it.

point is most people who have 300+ thousand miles used conventional the whole life of the engine. not saying all, but most.

 

If you wanna change to synthetic, I personally say go for it. I just made the switch yesterday in my XJ and no issues at all. Made the switch in my old Honda and drove it for about 50k before I sold it, not an issue in the world (obviously that is a completely different car and will react differently to a change like that).

Switching to synthetic has the potential of springing leaks, but that is just a sign that whatever gasket/seal/etc started leaking needed to be replaced anyways

 

I use three different types of oil
Mobil 1
Rotella t-6 ( best bang for the buck at wally world and cleans like a ****)
Penz oil
All high mileage of course,
I personally live Mobil 1 in my newer cars, but im going back to rotella for this xj because of the heaver operating temp and more zinc and detergents

 

I use Mobil 1 high mileage 5w30 in my 1989 renix. I'm on oil change number two and still haven't leaked a drop of oil. Front axle diff fluid now, I leak that a lot haha.

 

A lot of the whole Dino vs Synthetic war has been going on since the first synthetics started to become available to the masses. Back then, the synthetics had more detergents in them and those detergents would break up the gunk deposited by dirty dino oil that was coating engine seals and helping to seal the engine up. That is where the whole "synthetic oils cause leaks" came from.

Back then, the synthetic oils were arguably better than the dino oils of the day. They had more detergents and friction modifiers in them and that stuff did wonders for keeping the inside of an engine squeaky clean and really helped to reduce metal to metal wear.

However, that is not necessarily the case any longer. While synthetics may be better than some dino oils, not all synthetics are.

At the same time, the dino oils have gotten worlds better in just about every way imaginable. Most have similar detergents and friction modifiers as the synthetic oils. Again, not all dino oils are in the league of the synthetics, but most will provide ample protection for your engine.

Where the synthetics really shine is in extended intervals between oil changes. Some synthetics can maintain their lubricating properties for 15,000 miles or more. I am not aware of any dino oil that can go that long between changes without some pretty serious degradation to its lubricating properties.

I am not an oil engineer and I don't sell oils. I have used everything from Rotella, Amsoil, Mobil One, Pennzoil, Quakerstate, etc. I have never had an oil related failure to any of my vehicles. But I do change my oil and filter at very regular intervals (5,000 miles) and while it may be more often than absolutely necessary it is still cheaper than replacing an engine.

 

i change at 3000, but i use conventional with additives too. especially since i have this new engine. my old one was on its last leg and still lasted 2 years because of this method.

for the 4.0 conventional is your best route. not a cheap crap autozone orange bottle special but a solid namebrand high mileage conventional is still the boss.

however in my highreving LT1 modified engine for the maro' i run royal purple synthetic, because that what it is made for.

its like "right tool for the job"

 

Nobody here is an expert. Unless you devote tons of time to studying all of the ASTM, SAE, and countless other tests needed to even put a product on the shelves, with GL ratings and such...you don't know jack ****. Myself included. Yeah I've had training, have piles of literature, and good experience, but If you don't know what's in your oil, the real published test results, or whether its PAO base stock, or napthenic to begin with... you still don't know jack ****. And yeah, myself included...lol

 

right. im no expert either. but i get all my information from my friend and fellow jeeper who is certified and does know. im also not saying if you run synthetic your gonna blow up. but the engine is made to run with conventional and there are reasons for that.

 

I run this brand of oil in my 94 Country. Switched from conventional at 240,xxx miles and it's fantastic. 5w-30 is your friend sir, I live in Michigan so we have similar temperatures.

 

Certified?

 

hes got more automotive certifications than i knew there were.

 

Conventional vs Synthetic? Wow continued debate. Synthetic won't hurt anything but your pocket. Personally I like Snake Oil as I have been assured it is best. However with endangered species and all that I personally stick to conventional oil. I do apply the Hi Mi brands when on sale. I also don't mind bolstering a standard name brand 10W30 oil with 1/2 to 3/4 liters of Lucas oil stabilizer (a touch of the snake). I do see a difference in the duration of oil pressure thru the life of the oil. Bottom line for me is regular changes. I cahnge it every 5000 to 7000 km. For the Peep's travels, that's almost monthly. Just sayin it works for me.Typical week is just over 1200km. Runnin over 536000 km on the same 4.0L with great oil pressure and 3X more leakage than consumption. Fresh filter every time.

 

Well, I've done it 7 times and had no trouble with leaks. From Alfa Romeos, Datsuns, PT cruiser, Cummins NT400, Cat 3116, Cat 3126 Dodge 318s, and 360s. What can I say except maybe your vehicles were due to leak anyway.

 

The Peep leaks, seals have been replaced. Still leaks. Doesn't bother me till the dog does a walk under and then wants to be petted. I have no qualms against synthetic. I ran it (Royal Purple Synthetic) in the circle track Thundercar chev 350, excellent oil pressure when hot, 6500rpm at end of straights, changed 4X per summer season, engine still ran strong at years end with 5psi biggest drop in compression test, no leaks! Run it on the street bike CBR600RR, no issues over 10000 fast miles, rev to the clousds, changed 2X per summer, no leaks. The Peep XJ typically cruises under 2000 rpm on 1.5 to 3 hr trips, changed 12X per year. I run the conventional on the XJ and am satisfied with longevity for economy.

 

Check out bob is the oil guy forum and watch a test done with the "Lucas stabilizer " and see how it foams up and jacks up the oil hard core, they made a video of it, it basically foams and stays that way for hours, imagine running foaming oil, not good at all, and any good quality oil, conventional or synthetic will not need any additives like for normal use unless you are trying to clean it up (mmo/seafoam) I browse Bitog forums alot and some are engineers so I take there word for it,