'96 XJ 4.0 here and I was wondering what's up with this Mobile 1 oil I've just found. Website says it's good for a full year or 20k miles, whichever comes first. I've been using Mobil 1 high mileage/extended life and change out every 5k miles with a Wix filter. Should I switch over to this stuff and just change out every year (which is 10 k for me)?

Btw, apparently it's only offered in 0W-20, 5W-20 and 5W-30.

 

Personally, I would continue your normal regiment.
I know oils have come a long way, but I, PERSONALLY, don;t like the idea of 20k intervals. I know oils have advanced a lot in recent years, but oils brake down and I would rather do more oil changes than possibly needed, rather than less.

I dunno, call me old school.

 

That's the trick, these longer life oils do not break down nearly as fast as the conventional alternatives. But..and its a big but, the oil still picks up contaminates and the products of combustion. So what they are really saying is that their oil (and just the oil) is good for 20k miles or 1 year. Meaning it will hold its critical properties that long. But they aren't vouching for how clean or not clean that oil will be. I think on newer cars, that are far more efficient, sealed better, and get fewer combustion products into the oil perhaps its a realistic option (debatable). But on an older I6, I wouldn't do it.

I'm curious if they have fine print that says that you would still need to change the oil filter during that annual period. I haven't seen the product on the shelf, so I don't know.

 

While the oil might hold up that long, what about the acidic combustion by products?
Maybe the that oil can neutralize them? What about filters holding up that long?

I will keep changing oil every 4 to 5k miles. Besides its a great feeling knowing you replaced that funky old oil with fresh oil and a new filter.

 

I was pretty skeptical when I saw the product. the asterisk on the back of the bottle says to change at 20k or the recommended interval specified by your owners manual. I couldn't really tell if this is the same oil with a different bottle and price or actually a different oil. I'm going to stick with what I have been doing: synthetic and 6,000 miles or 6 months.

 

Wow, that's some BS on the back of the bottle. What car/truck has an interval of 20k? I just don't understand it. Oil changes are by far the cheapest insurance you can give your vehicle. I could understand if an oil change is hundreds of dollars but it's like $40 for our Jeeps tops.

 

Meh I've been changing the Mobil 1 extended oil in the wife's KIA every 15k since new, it now has 160k, I've had zero issues and i will switch over to this new oil for the next oil change.

 

Just put this stuff in my wife's 13 cruze. I plan on changing it in less than 20k miles. Plus its like twice as expensive almost

 

I suppose if we had one, Salad would be our "resident" oil guru. >> https://www.cherokeeforum.com/f2/rot...essing-188168/

 

I drove a '93 Ford Taurus as my first car, had it 5 years ('06-'11). I had the oil "professionally" changed by some guy who had a garage attached to a Walmart, and then changed the oil ONCE myself after that. So in the 5 years of my ownership the oil was changed twice. If I haven't made you cringe yet, I drove it 4 miles each way down a dusty dirt road and another 20 miles to school/work every day.
Now the reason I tell this story is because
1) I like to make mechanics cringe
2) The only reason I got rid of it is because the throttle cable snapped and I had my jeep by that point. However just a month before that it passed DEQ with flying colors and was for all intents and purposes a very well running vehicle.

Now should you follow my lead, probably not. I've now lost my train of thought and don't remember where I was going with this but perhaps you can come to your own conclusion about what I was thinking.

 

UOA's for me were showing me pushing my limits with the best oils at about 8k miles. Sure, oil can last a long time these days, but contaminants are still contaminants, and oil filters are still also limited capacity. I don't spam the UOA's anymore and just use PYB 5w30 on a 5k mile OCI. Multiples of 5k are very easy to remember/recognize on the odometer and work out to about 3 oil changes per year for me which also coincide very nicely with tire-swap time (winter/3-season tires). I've found my perfect system.

 

Thanks for posting that link of Salad's. One excellent read on oils for our 4.0s.

I've always suspected these old 4.0 designs are really tractor engines.

 

I think that Mobil 1 is a rip off for the price. The high OCI is offset by the high price. Like others have said, contaminants is what ruins the oil. In years past I have done a few UOAs on my vehicles (Jeep included).

My wife's car (Ford Freestyle) gets the oil changed every 10k, and my XJ every 5k using Supertech synthetic 5w30 in both ($17 and change for 5 qt jugs)

I did a few UOA with Blackstone, and they recommended 12k for the Freestyle, and 6-7k for the Jeep. It was easier math to just do the 10k and 5k so that's what I have been doing for years.

I can't justify $50 for 5 qts, when the Supertech is $17 for the same quantity and I have had the UOA to back up my OCI mileage.

 

A lot of diesel truck drivers are pushing 30K miles on their oil changes because otherwise they would have to be in for service pretty much every month, and for them it's not just the cost of the service but also the lost revenue from time off the road. In a fleet situation, that also adds up. Those guys are usually running heavier filtration.

A 20K miles service interval might make sense in other vehicles if you're driving them ridiculous amounts of miles, especially in a fleet. If I'm a fleet manager and can safely double my interval without significantly increasing wear on the engines, I cut my annual normal service cost in half.

 

You mean, you guys haven't been doing annual oil changes?