bakesale1

I have a '91 Cherokee and am considering switching over to synthetic oil. Anyone have any thoughts?

RaiderMike67

Oreilly usually has some good deals on oil/filter combo's for under $30. I can crawl under my Cherokee and do an oil change with out jacking it up, if you need to jack it up make sure to use jack stands!

XJMichael

I'm considering switching to synthetic as well I've just heard alot of guys talking about how much better it is for the engine

Creature85

My 04 GCL runs cooler and generally better on synthetic. Though this topic has been debated a million times I'm sure on every car forum and you never see everyone completely agree with one another. I'd say try it and see how you like it. I run Mobile1 Extended Life in mine.

Artful Owl

Then you have to decide on the grade
The Jeep handbook recommends 5w/30 - but the handbooks in the auto part shops recommend 10w/40 semi synthetic.

I had the 10w/40 semi synthetic added when I had a new sump fitted to my WJ V8 recently.

Creature85

Right, I use 5w/30 as per the handbook's recommendation.

bigbadon

5w30 is the government mandated recommendation.
10w40 is the mechanics and automotive engineers recommendation.
Jeep tried to tighten the clearance tolerances on the 4.0 in it's last years of production but it was an ill fated attempt. Be safe and run 10w30 or 10w40

bakesale1

Yeah, I used to run 5w30 but on a 20 year old engine with 200000 + miles on it, 10w30 works a little better

Xj88

I ran T6 Rotella 5w40 in my XJ. Great oil, pretty cheap, full synthetic..
Great oil IMO

Now in my TJ I run 10w 30 Mobil 1 Full Syn (2.5L I4)

Xj88

Btw..if you do swap to full synthetic make sure you stay with full synthetic..dont go swapping between dyno and full syn.

Also, get a qualilty oil filter..mopar, napa gold, bosch.

Creature85

How do you like the Rotella compared to the Mobile1?

beedees

Just out of curiosity, exactly WHAT is syn. oil made from? Another great mystery of the universe, I guess.

c.morris740

I run the rotella 5w40 in mine. Haven't really noticed a difference. Seemed to quite it down a little about it. But with 250,000+ miles its to the point where I don't really worry about it.

I was always told dont run synthetic unless that's what was originally put in the motor but don't know why.

bigbadon

synthetic dinosaurs and future landfills

Bustedback

I just switched to Chevron 15w40 from Quaker State 10w40. I noticed my engine is slightly quieter and the oil pressure stays higher longer. Also using a WIX filter.