I wanted to know what gear oil everyone uses. I am going to change mine tommorow and wanted to know what the best one is. I know royal purple is up there, but i want to use something else not so expensive.

 

I use mobil 1 because it's almost half of what royal purple is, and i have a good amount of faith in it. for 75-90

 

I'll second that. If Mobil 1 gear oil was available here thats all I would use.

 

If you gonna change it as per the owners manual ... go with the expensive stuff.

If you are gonna change it after any water forging ... go with the cheap stuff ...

 

I plan on changing my gear and transfer case oil every 15K. Changing it that often negates any true benefits a full synthetic would have over the stock stuff.

I work for a body shop, so I can get Mopar brand oils and LSD additives at cost +10%.

If you plan on changing it often, I would recommend going with the factory stuff.

If you are not going to change it often then I would say go with the Mobil 1.

I have heard bad things about Royal Purple in the JK's so I stay away from it. Its comments that I have heard mostly from the internet, so it must be true.

Good luck on whatever you decide.

 

Just remember the Mobil 1 does not need additional LSD additives.

 

Thanks everyone, I think i wil go with mobil 1. Now all i have to do is find it. I was at one of my local auto parts stores today. All they had was the cheap stuff and royal purple. I guess i'll have to check all of them now.

 

The bad thing about using Royal Purple lubricants anywhere in your vehicle is that the dealer will always know it is not factory ... and may cause warranty issues if you end up with a bad tranny, engine or differential.

 

Perhaps we should all refer to the owners manual before spreading 'warranty voiding' rumors. 'Meets Daimler standards' does not mean 'must purchase from dealer'...
(it says you can use synthetics, as long as they meet the standards, and for towing, they specifically tell you to run a synthetic...)


Engine Oil Selection
For best performance and maximum protection for all engines under all types of operating conditions, the manufacturer recommends engine oils that are API Certified and meet the requirements of DaimlerChrysler Material Standard MS-6395.

American Petroleum Institute (API) Engine Oil Identification Symbol This symbol means that the oil has been certified by the American Petroleum Institute (API). The manufacturer only recommends API Certified engine oils.

Engine Oil Viscosity (3.8L Engines)
SAE 5W-20 engine oil is recommended for all operating temperatures. This engine oil improves low temperature starting and vehicle fuel economy.

The engine oil filler cap also shows the recommended engine oil viscosity for your engine. For information on engine oil filler cap location, refer to the “Engine Compartment” illustration in this section. Lubricants which do not have both, the engine oil certification mark and the correct SAE viscosity grade number
should not be used.

Synthetic Engine Oils
You may use synthetic engine oils provided the recommended oil quality requirements are met, and the recommended maintenance intervals for oil and filter changes are followed.

Materials Added To Engine Oils
The manufacturer strongly recommends against the addition of any additives (other than leak detection dyes) to engine oil. Engine oil is an engineered product and it’s performance may be impaired by supplemental additives.

Engine Oil Filter
The engine oil filter should be replaced at every engine oil change.

Engine Oil Filter Selection
All of the manufacturer’s engines have a full-flow type disposable oil filter. Use a filter of this type for replacement. The quality of replacement filters varies considerably. Only high quality filters should be used to assure most efficient service. Mopart engine oil filters

Axle Differential (Front) Mopart Gear & Axle Lubricant (SAE 80W-90) (API GL-5) or equivalent.

Axle Differential (Rear) 198 RBI (Model 35) and 226 RBI (Model 44) - Mopart Gear & Axle Lubricant
(SAE 80W-90) (API GL-5) or equivalent. For trailer towing, use Mopart Synthetic Gear & Axle Lubricant (SAE 75W-140) or equivalent. Models equipped with Trac-Lok require an additive.

 

I have another question. Is there mouch of a difference between the 75w-90 and the 80w-90 the manual calls for?