Oil recommendations

[Saudade]

There's always a cost difference between "direct fit" and Universal. Add in "50 State/CARB Certified" and it jumps at least another $100 or so.

A direct fit, CARB compliant cat for my '88 is currently $700. The universal is $500. These are both Walkers.

 

[Rob Mayercik]

I'm using rotella 15w40, I change it so often because it's my mail jeep and that's how long it takes to rack up 3k.

Why do you think you need to change the oil every 3K? Did you base that on actual data, such as having used oil analyses done?

When I doing 500-600 miles per week on my XJ, I was using basic non-synth 10w30 in my 4.0 and it was barely getting the oil dark at 6000 miles. I probably could have gone further, but 6000-7000 was a number I was comfortable with at the time.

I know you're doing all stop-and-go driving, but you're also keeping the engine up at operating temperature for long periods of time (couple hours or more) at a time, right? That's probably the next best thing to long-range highway cruising.

15W40 may be a little thick for cold mornings, the 10W40 may be a better all-around choice since these engines called for 10W30 originally.

I'd say switch to 10W40, and extend your change interval out to at least 6K or more miles. If you're that uncomfortable with that, get an analysis done (someone like Blackstone Labs) every 3K, but there's no reason a good-quality oil can't go that far in a 4.0 these days..

 

[Unclewolverine]

It's been low on power since I put it in, oil is almost black at 3k. Just trying to keep it running as long as possible. Don't know when I'll get around to building a new motor. I change the oil in the wifes '12 escalade at 3k too even though it says it can go 15. It's just what I do.

 

[Rob Mayercik]

I can't even imagine what's going on in there if it's turning the oil that dark that fast. I wonder if your injectors are overfueling or something. Has the computer thrown any fault codes?

 

[Unclewolverine]

Ha. The computer didn't even throw a code when the old motor puked a rod out of the pan. Injectors are probably bad, 300k on probably original Injectors.

 

[Rob Mayercik]

I put a set of Bosch 703 injectors into my 92 for around (or possibly under) $100 a number of years ago. That's only the cost of 1-2 oil changes.

There wasn't anything wrong with my original injectors at the time (and I didn't notice any real difference once I put the new ones in), but I decided to play it safe as they had about 235K on them and a NAC member at the time with a 98 had just had an injector fail at 305K and wreck one cylinder.

I threw my old injectors in a ziploc bag, and they've been sitting in the garage ever since as emergency spares. I wonder if they'd be compatible with your rig?

 

[Unclewolverine]

One day I'll get around to buying a set of 4 holes. I have a 258 crank so when I build my new motor I'm probably going stroker.

 

[Vince]

When my '93 was built and shipped to the UK as an export model the service intervals on the original equipment service schedule was for 10w30 at 7,500 miles or six months whichever came sooner. My 2001 had the same interval in it's service schedule and so did the TJ's all with 4.0L . I have always used that interval in the UK and in the USA and not had a problem.

The JKU I had in Switzerland with a 2.8CRD was 20,000Km interval (no time limit) but the oil specification was very particular for Switzerland and cost roughly $30 USD a quart. Sold it at 85,000Km and it was still like new with just four oil changes in three years.

12-month oil change intervals were common in the 90's for European brands. Only Chrysler and Jeep had six month intervals here. Most manufacturers are now on 24-month intervals including a lot of Stellantis brands. Engine oil is expensive in Europe so ordinary people that just use cars don't mind long intervals.

My parents have leased cars for decades and usually change them every 3 years. An annual service was common up until 2015 but the last two cars have only had one service. The dealership arranges the service and collects the car to do it. The lease company uses tracking telemetry to decide when the service is due.

Oil analysis is the only way to know how good or bad your oil is. I can no longer find blends suitable for flat tappets at car part suppliers. I am now buying specialist 4 stroke motorcycle blends in 20L and 25L drums in API SJ 10w30 for flat tappets. Had cats replaced on both XJ's within last 2-years. They never last long on my Jeeps because they don't like being dunked in mud when they are hot.