theoldniner

Hi friends and Cherokee colleagues!

I live in Central America ("the nice tropics" hotter than the hell) we have normally 80 to 88 ℉ as a daily average temperature...
My ZJ 5.9 1998 GC is now on 34500 Kilometers on the odometer, but yesterday a guy in the mechanics shop say I may change my oil to
20W50 due to the high temperature and "hi power" engine I have...

So I did it...

-Is it true?

-Is the 20W50 a better oil for my 5.9 motor?

-Is my motor in danger to be damaged?

Thanks in advance for all the answers and kind advice!!


my 5.9 motor.

00t444e

It's not going to hurt anything, I run 15w40 in mine all year round, I wouldn't put any higher then 20w50 in it.

theoldniner

Thanks for your nice and FAST answer Mr. 00t444e!!!!!
So, think I can be more relaxed now...

Thank You very much Mr. Have a nice weekend!!!

4.3L XJ

I live in CA and use 20W50 in my high milage vehicles

theoldniner

Thanks for your kind answer 4.3L XJ. Nice weekend to you!!!

4.3L XJ

No problem. One rule that I go by is that as the engine wears, or in areas where it is hot, increase the viscosity of the oil. Old race guy go as high as straight 50W in their hopped up engines

theoldniner

Yes that's one of my worries... My have only 35K miles walked... But if you say because the temp is Ok, so: It's ok for me...
Thank You again Mr. 4.3L XJ!!!

Kymasabe

I run semi synthetic 10w30 in mine, and I'm in subtropical SW Florida. Chevron Delo, or Shell Rotella T5. 170k miles and no problems so far. In the hotter tropics, I might bump up to 15w40, but I think 20w50 is pretty thick.

Rock36

I run 20w50 in my '71 Pontiac Lemans 350V-8 and seems to keep her healthy but she has almost 250K miles on her. Did I read right your's on only has 34,500 kilometers? Or are we missing a zero?

dave1123

My 2000 WJ with the 4.0 is very tired at 250K miles and has a cracked piston skirt (probably) and low compression. I switched to Shell Rotella T6 5w40 synthetic diesel oil and it runs smoother, uses less oil, and has higher oil pressure at all rpms. It is quite pricey at $30 USD per gallon, but it's designed to run at the higher diesel temps and has additives that plate bearings. I live in the colder climates of Upstate New York where it gets well below zero many nights or even days at a time and it still starts easily. I credit this oil to have given me roughly 25K more miles life out of this tired old motor. Problem is it only comes in GALLON bottles, not 5qt ones. In my area Advance Auto Parts has it on sale many times for $10 off a gallon so I buy it during the sale. It was recommended to me by the guys on this forum that I trust.

This may not be what you're looking for, but I just threw it out as an option. Gotta keep that rare 5.9 alive!