got an 090 mopar filter

 

I personally run rotella 20/50 and a wix filter. Or ill run a purolator if merles is closed or i don't feel like driving 20 miles

 

Wallyworld does seem to have the best Rotella prices. Problem is around here they don't stock a lot of different weights.

The 'T6' is full synthetic, the 'T5' is synthetic blend which i've been using.
Might upgrade to T6 next oil change to see if it improves oil psi better in hot weather.

I use 10w-30 in Winter and 15w-40 in Summer.
I personally stay away from straight weights.

 

why such a thick oil?

 

 

That movie has always creeped me out haha

 

Eat more chocolate while watching it.

 

4.0s run fine on a 40 weight oil, I believe that is what they originally called for, diesel oil has additives that help prevent wear better on flat tappet engines then modern gas engine oils do.

 

15w40 diesel oil is fine to use I am switching to Delo 15w40 on my next oil change but shell is fine too.

 

I run

15w40 in the summer
5w40 in the winter

Jeep seems to love it. Usually Shell Rotella

 

I run such a thick oil because I have a tick and I live in the Arizona desert. It helps quiet my motor and I haven't run anything else in 3 years

 

Jeep Engine Oil Viscosity

This was taken from pages 82 and 83 of the 1989 Chrysler/Jeep owners manual.

Selecting Engine Oil Viscosity

When changing or adding engine oil select the proper grade by using the chart on the following page. Select the grade that corresponds to the ambient temperature range you expect to encounter before your next oil change.

30*F to 100*F+ 20W-40 or 20W-50
0*F to 100*F+ 10W-30 or 10W-40
-20*F to 60*F 5W-30

 

20/50

 

i run t6 in mine. wix 51515 filter. good news is my truck takes the same filter.

 

I love Rotella. It sucks I can't find any 5w 30 for my Wrangler's 3.6L or else I would continue using it. Now I use Pennzoil Ultra Platinum.