the best fluids?

[KC]

ok so i have 5w30 engine oil and i have no idea what is in the tranny because i had it rebuilt last year and dont know what the guy used. So what is the best to put in right now. full synthetic? and maybe 10w30 because of the temp.? and for the tranny what is the best stuff? when i go to start the jeep in the early morning it struggles to get started, and the shifter and clutch are so tight/hard to move....any suggestions?

[BlackYJ]

I run dino 5w30 in the winter, but I have been thinking about synthetic.  If I were to run synthetic in the engine is probably would be Royal Purple.

As for the tranny, we need to know which tranny.  The AX-5 and AX-15 take 80w90 oil and the NV-3550 takes synchomesh I believe.  I ran for the longest time dino 80w90 but last spring I put in Redline synthetic 80w90 and it made a big difference.  Smoother shifts, easier on cold days, and made the tranny quieter.  I have the AX-15 with 220,000 kms on it.

In the t-case, which take ATF, I put in Royal Purple synthetic.

[KC]

ok so how do i know what tranny i have...i have a 91 YJ 5spd does that help?

[born2jeep]

if you have a 4.0L then you have a AX-15

Sam

[Waytec]

Heres my 2 cents.
What I find works the best is go with what ever the manufacture says. For the engine change it more often or after some really hard abuse. In the trany I use manufactures spec with a lubercation additive, manly Lucas oils. The only differences between Canadian tier brand 5w30 and Qastral high performanse 5w30 is the additives in the oil. If you go with a synthetic or a blend look at the additives they are what make the differences.
I personally don't think synthetics in the engine make a big difference for the normal driver.
Every on youask will give you a different option what you need to do is research it an try some combinations until you find one that works for you.

[Rookie]

If you switch to synthetic odds are you will get leaks and if you have leaks they will get worse

Dino oils molecules are all different sizes so the big ones help stop the small ones from leaking out, synthetic molecules are all a uniform size (small size and they seem to prefer to be outside the engine)

I tried it myself 220,000 km on mine ran synthetic for 3 months and the rear main started to leak switched back to Dino and now it still weeps . Could it be a coincidence maybe but if you read up on the American forums it happens allot

[yjcanibul]

I only run synthetic in engine (4.2L with 4L HO head ) ,  some years ago parking outside in the dead of winter ( -35c) it was hard starting and noticed a slight valve tick till engine was at least cold,  switched to castrol syntec (same weight 5w30) in the midst of 10 day cold snap and started x2 better and tick was gone ... been a believer since ...

for rest of drivetrain I use std dino fluids just change them as required ...

[SwampSinger]

I run synthetic on the 4.0L now... it started leaking (more than sweating)  when I started to put synthetic in it. I have about 180,000 Km on the ol' Cherokee....

I will change to regular good 5W30 and add a Lucas racing additive on my next oil change.

I run Synthetic ATF in mt T-case and Synthetic 75W90 gear oil with Lucas additive in my tranny. I had issue with shifting gears before... It shift like BUTTAH now  !

I recommend Lucas additives... it made a whole lots of difference how my Jeep drives.

That's my 2 cents...

[Waytec]

Could you guys tell me where a good place to get Lucas oil from in town.
I need to change the fluids in the t case, trany, and diffs.
thanks.