XJ-NC

Just wanted some thoughts on whether you run synthetic or regular motor oil and why?

I want to make my XJ last as long as possible, so I'm thinking about running synthetic, but I've heard it's not worth the cost if you change the oil every 3 months or 3K miles.

xjjeepthing

Alot depends on the mileage of the motor. At high miles synthetic really has no advantage. I've ran both, can't justify the cost of sythetic over regular. Change it every 3,000 and you should have no issues. I do run synthetic diff lube, I think it help with moisture and keeps the bearing and gears in good shape.

01XJBES

Synthetic oil has way better lubricating properties than mineral oil. My buddy ran completely out of oil in his dodge stealth twin turbo and it didn't even get lifter tick. He blew an oil cooler line and drove to a store bought more synthetic oil and drove home to find that he had no oil when he got home.

stumper

i use it for our really cold temps here. it just flows so well at low temps, it's easier on the starter and battery, plus the vital engne parts that need oil get it right away. i run it also in the diffs. it also has an excellent high temp property to it. ya, it costs more, but the trade off i think is worth it.
my opinion.

jinx

Full synthetic. engine builders recommend that you not use it in a new or rebuilt engine because it wont let the new parts wear in properly. thats proof enough of how well it lubricates. also you can go longer between oil changes.

NeosXJ

I am a huge fan of synthetic, especially Mobil 1... I had a '95 Nissan Altima that I bought new as a daily driver, after the first 10k 'break in" miles, I ran nothing but synthetic, changing it every 5k-6k miles. When I replaced the valve cover gasket @ 190k miles, the top of the engine was spotless: no crud, no gunk, just nice golden-colored metal. I sold it to a friend last year, but it now has 220,000 miles and still runs great.

I run it in my $500, 120,000 mile Cherokee and it doesn't leak at all... (It burns about a quart of oil every 5000 miles.)

Bottom line: Highly recommend it!

jpdocdave

i'm not for it, many have reported oil leaks when putting synthetic in high mileage engines. i've read the scientific explanations in research on the matter, i won't get into now for time sake, but it makes sense with the smaller molecular make up. and there's many that lose track of time, and think oh its synthetic so they end up changing their oil once or twice a year. besides, the 4.0 has been around since before synthetic oil was even an idea.

i use valvoline max life in all my jeeps. every 3k. i work for a shop that is a valvoline store, and i buy the max life at walmart for $14/5qt jug.

the filter is the important part here. the only filters that are worth while are wix, also labeled as napa gold, and carquest blue. there are some very crappy filters out there. i've actually taken off quite a few cheap oil filters that had loose parts inside.

look at the make up of oil filters, the amount of media, and the cheap ones that use cardboard by pass valves and stuff like that. lots of people buy mobil 1, and then a fram filter.

this is well worth the read: http://www.knizefamily.net/minimopar...ence.html#fram

jpdocdave

oh yeah, i haven't done a ton of research here, but the gear and locker manufactureres, such as arb, and i can't remember some specific names, but they are saying if you run synthetic gear lube it will void the warranty. the've found that the synthetic is not disipating heat very well in diffs. and i guess royal purple diff fluid is absolutely terrible on new gears set up.

fatnred

im not positive on oil performance but im pretty sure that jeep used to run quaker state for there new units, would it make sense to stay the same? im using quaker high milage and same with fellow sophisticates and havent had any bad feedback.

jpdocdave

last time i looked quaker state is made by penzoil and i stay away from penzoil. perafin based oils turn to sludge. i would only use castrol or valvoline.

but if you are consistant on oil changes on time, any decent oil will be fine.

i've just taken apart way too many engines that ran penzoil only, and they were caked.

fatnred

yea havent had any prob will stay with same routine, i have been adding the bg line of products to my fluids and and all seems well but i keep reading posts about seafoam and i spoke to a jeep tech and he said dont even bother with the product stick with bg whats your insight on seafoam?

jpdocdave

i've never tried seafoam. lots of people love it. i would recomend an engine flush every once in a while. super easy, you buy the flush chemical at the parts store, its mainly keroscene, poor it in the oil and run it for 5 mins. then change the oil. it actually works, and cleans the junk out really well.

fatnred

thanks again, and on the flush its not prone to ruining any seals or gaskets is it and if not how often do you recomend this procedure

jpdocdave

perfectly safe, i've done many. if you change your oil on time every time you don't need to very often. if you haven't had the vehicle since new i'd do it no matter what. after that maybe every 30-40k

Phil99

I got 142000 miles and I'll die by my synthetic oil