2001xj

well i switched to synthetic mobil one 5w-30 on christmas day and no i am leaking oil i am down a quart and it is leaking from the filter and top of my oil pan. should i switch back to dino oil.

XJ Stryker

Switching oils is very unwise on a older vehicle.

2001xj

if i switch back will it fix itsself??

Mudhunter241

you should fix the leaks. I wouldnt switch back. Spend the 20 bucks to fix the leaks

XJ Stryker

Nope you have created them now you have to fix them. If you want to run synthetic then keep running it but you will have to deal with the problems like leaks that can occur when switching oils. Soon your engine and seal will get used to the new oil and it will be fine again.

5spd-XJ

Why such a thin oil? I use 10-40 year round no problems

2001xj

live in michigan

5spd-XJ

Cool, I'm not trying to make you change your oil type by any means. I was just wondering. everybody has their own preferences when it comes to oil viscosity/brand and so on. Just make sure the oil you use has the additive "ZDDP" it helps form a protective film on the cam and lifters IDEAL for flat tappet cams IE: older style push rod type engines. Most new oils don't use "ZDDP" because the Gov. decided that ZDDP was one of the causes of cat converters failing sooner than they should. Thus new oil must not have any ZDDP added. Of course you can always by a ZDDP oil additive, or use "high mileage" oil.

whowey

Not true....

What happens is that the dino oils leave behind crud,gunk,mung and it builds-up. Seals that are worn let a tiny bit of this stuff to build-up in the leak and it closes off.

Synthetics contain a MUCH higher percentage of detergents than dinos. So these detergents clean out the crap left behind by the dino oil and the leaks appear.

So the OP didn't create the leaks, neither did synthetic oils. Just plain wear created the leaks. The OP simply cleaned the crud out that kept the leak from being seen. The chances are good that the seal was actually seeping a bit. But now he needs to fix the leaks, they won't go away.


When you are looking for the correct oil for a 4.0l, you are looking for oils that meet the API-SL rating. This rating still contains enough Zinc and Phosphorus for the 4.0L. ZDDP is simply the compound that contains the Zinc and Phosphorus.

BowtieGuy3

Actually, the difference between 5w-30 & 10w-30 is negligible, and the diff. between 10w-30 & 10w-40 are negligible at freezing. Just a lil FYI...