doing an oil change anyone recommend a good oil to use? i got a 98 I6 4.0 with 172k on it and i live in nh so the weathers getting cold

 

Valvoline 5w30 in the winter months.

 

New? Pick a brand... I run a 10W-40 all year but I live in GA.

 

You goin to river rock this weekend?

 

I run the 5w30 Walmart SuperTech high mileage in the Winter. It's great stuff and reasonable.

 

I buy whats on sale of either 10-30 or 10-40, at 210K it works for me

 

i use quakerstate 20w50 and a bottle of lucas oil stabilizer,yea its thick but thats all thats been used in my xj,it runs good with it to

 

wow that way too thick for the 4.0L

stick with SAE 30 like the designer's intended.

5w30 is preferable, 10w30 is acceptable

 

I just bought my 98 with 96K and the previous owner was using 5w30 Mobil 1 Synthetic. I suspect I will stick with synthetic, but may change to Amsoil.

 

my step mom bought it brand new from the factory with 20w50 and thats all it ever had in it,ive been told by many mechanics that know the 4.0 in every way possible and they all said its good to run thick oil wit any straight cylinder motor

 

From what i understand you're never supposed to use anything but synthetic once you run full synthetic. Or at least that's what i've been told, something do do with the seals

 

You can go back after running synthetic if you want to. Its your choice but synthetic cleans much better than conventional so its more of a waste of money to swap back.

 

I heard you should only run conventional in a brand new engine, to break it in. then after that run synthetic

 

synthetic is a much more stable oil but runs alot thinner when it gets hot. it is what i like to call leak test oil, if you car has a leak, synthetic oil will find it. older engines have a hard time running syn oil cause the seals on older engines were not made for it, like the newer engines these days are. i use 5w-30 Valvoline High Mileage in my jeep and never had a problem. i have 172000 miles on my jeep but have a rebuilt 4.0 in it, i bought the jeep with a blown motor...due to lack of pilot bearing. what a F***ing idiot!!!!

 

Wow, 6 myths in 12 posts........typical oil thread.