XJ 4.0 Oil Thread 2020

[It'sBigAl]

Originally Posted by alexbrown64

Big Al, do you have the 4.0 in your ZJ?

I went on the Gulf Western site, and searched for the recommended oil for a 4.0 Jeep Cherokee and it came back with Euro Energy 5w/30.

Density @ 15°C ASTM D1298 kg/L 0.852
Kinematic Viscosity
@ 40°C cSt60
@ 100°C cSt10.0
Viscosity Index ASTM D2270 - >150
Pour Point ASTM D97 °C -34
Flash Point (COC) ASTM D92 °C 210
Total Base Number ASTM D2896 mgKOH/g 7.9
Sulphated Ash ASTM D874 % mass < 0.80

The site gives a basic read out for each oil, but no figures on additives etc..

Cheers,

Interesting. For a ZJ, exact same motor, it recommends

SYN-X 6000 5W-40 API SN/CF Synthetic ACEA C3

SYN-X 5000 10W-40 Synthetic SN/CF A3/B4 VW 502/505, MB 229.3

SYN-X 3000 10W-40 SN/CF Semi Syn

Which is what I use.

Personally, I think in an Australian summer, with a vehicle that runs as hot as ours do, 5w30 is simply too thin and will thin out too much. As for using the semi synthetic, I don't believe an engine as old in it's design as ours really warrants full synthetic oil. Maybe I could extend the change intervals a bit if I went full synthetic, but I'd still probably do 7500 km changes anyway.

[It'sBigAl]

The other thing to bear in mind, when selecting viscosity grades of oil, is to take any recommendations from the US, either first or second hand with a massive grain of salt.

Their CAFE (Corporate Average Fuel Economy) standards mean they will recommend the absolute thinnest possible grade of oil they can get away with, to try and get any gain in mileage and economy they can possibly hope to. Their standards are brutal and they'll run 5w30 or even 0w20 instead of 10w40 and make a 300,000 mile engine a 200,000 mile engine if it gets them just under the standard for the year.

This is why most cars recommend these super thin oils while a lot of diesel trucks which are under a much less stringent standard still use 10w40

Not to mention the difference in climate in the US. Large swathes of the US have massively cooler temperatures than we do, where temperatures of 30 degrees are unusual and limited to one or two months a year, not 6 months like we do. I'd be taking advice from someone in Arizona or Texas over someone from Minnesota over oil thicknesses