Jeep 4.0 over 100,000 miles. Too late to start synthetic. I'd like to stretch out my oil changes, about every 6 weeks or so now with the miles I drive. May also help fuel mileage a bit. Just don't want to spin a bearing or blow it through the valve guides for this little savings. The engine still seems tight and oil color is good.

 

LOL, if thats the case, I am in deep doo-doo.

Started my 94 squad at 142K on a full diet of Moboil1 and she who must be obeyed's 98 Grand Cherokee on a diet of half synthetic at 189K........

If you have no leaks or oil use now, you should be fine, at least I would switch it if it were me.

 

Just change the oil filters a little more often and add the make-up 1/2 to 1 qt to compensate.

 

Go for it, from what i've seen in the field the old switch to synthetic problems are just myths, huh maybe someone should submit that one to mythbusters.

 

I think a lot of the stories started back when Synthetics were new and engines just were not held to the tolerances they are today. I can clearly remember 50K mile engines in the late 70's start to leak when switched.

That being said, I had no hesitation to change mine, and once the 97 is relatively leak free, I will switch it over also.......( I hate to lose the Rotella smell though...)

 

I can understand that although i never saw the 70's (i was born a couple years after they ended, lol.) Theres lots of auto rumors like that out there that stem from the "old days" that hold no truth today though.

 

We are po' folk so I always bought high milage used cars, switched every one to Mobil 1 since it was available in the early 70's. No problems.

 

Sounds good guys, thanks.

 

the only problems I have heard out of switching a high milage vehicle is oil leaks from the synthetic cleaning the sludge out of the engine...

 

Put on a Frantz by pass filter and go for the long drains.Some info here. dinohttp://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=977051#Post9770 51