I've had my Cherokee for about 3 weeks, but it didn't come with any kind of maintenance records. So I'm going to go out and get some fluids and take care of all that . It's a '91 Laredo. 5SPD. 4.0L. 4X4. What kind of fluids do you guys use for

Oil
Manual Transmission
Coolant
Differential

 

Oil - 10W40, Castrol non-synthetic high mileage (might switch to 20w50 in summer)
Manual Trans - I have auto, so no help here
Coolant - Prestone 50/50 mix (saves me the trouble of mixing it up myself)
Differential - Mobil 1 full syn 75w90 (go to 80w140 if you tow a lot), and don't forget the friction agent if you have limited slip

 

why do u use 10w40? just curios

 

as far as oil Iuse Mobil 1 full synthetic. i am a mechanic in the coast guard and we use in everything from the boats to the jets. i use the prestone 50/50 with redline wetter than water(has corrosion protectant) i am getting ready to do my diff so I havent decided what to use, but if mobil 1 has a product i will more than likely go that route

 

I did my front and rear diff last weekend. Used 3 bottles of the Mobil 1, and had a small bit left over. I have a D30 front, 8.25 rear...just FYI for when you go to buy it. I didn't think it would be near enough...but it did the job. 1 tube of RTV Black.

Why do I use 10W40? Guess it would help to answer if I knew which side of the fence you were looking from. You think that is too heavy, or you think it's too light?

I use it because it was recommended by a bunch of others on various boards and by a bunch of the guys I work with (all retired and current ASE techs). Some guys even go heavier, to the 20w50 I mentioned. I will next summer, as Texas summers are hot as hell and I get stuck in traffic a lot. I think with the age on our engines, and the strain we put on them off-roading, it's believed that the heavier oil helps a little bit. Some guys even run the heavy weight diesel oil in their rigs. Also, the older an engine gets, higher mileage....you will generally see more clearance. Thicker oil helps fill that space. Or at least that is my understanding of it (I am definitely not a mechanic....just learning as I go along).

 

I changed the oil right after I got it.
Valvoline MaxLife High Mileage Semi-synthetic 10w-40
The leaks (very small) havent seemed to speed up any with the synthetic blend, as some say they might..
I havent changed the diff fluid, or done anything to the trans or radiator yet. The diff fluid smells/looks new, the trans fluid looks fine, and the coolant is a bright green...

 

Oil = AMSOIL 20-50 high zinc formula (this summer), or MOBIL 1 15w-50
Manual Transmission = REDLINE MT-90
Coolant = Peak 50-50
Differential = MOBIL 1 75-90 or LUCAS 75-90

All oils are full synthetic

 

10w40 only if you have a bad engine knock. That is on the heavy side for the lifters.

I have 180,xxx on my engine and Amsoil 5w30 works great.

 

so if i have lifter noise use the 10w 40?

 

Your from the midwest? yeah for this time of year 5w30 sounds about right
Here in northern cal, the summers get 90-115 deg, so I run some heavy stuff.
Plus my motor is on the high mileage end of its life
Right now though, the only noise I'm hearing from mine is the a/c pump bearings whining
Ugh *shudders*

 

I would not use a thicker oil with lifter tick. I have a mild lifter tick and when I switched to 10w40 it was worse. You want the lifters to build pressure on a cold start. Too thick of a low vis will prevent this, ie: the 10w, 15w or 20w portion of the API rating.


True. But 20w50 is still a little too thick for me. But if it works for you, thats all that matters.

 

Ten-forty is a good multi weight oil.
lifter noise, or similar noises, are caused by tolerances that were once close, opening up (wear)
Thicker viscosity's tend to quiet these noises.

 

d p
sorry

 

d p
damm, lag!

 

Wait, too thick caused more noise?