Controversia Lubrication fluids for Giddyup …. Need advice … PLEASE and Thank you !!!

[seafish]

Time for some 10k and 60k fluid changes.

ATF+4 in the AT and TC is easy, but below are the more controversial questions—

ALL opinions welcome but please no fighting … TIA!!!

I live in a completely temperate climate with outdoor temperatures rarely below 44° and NEVER below 30° and then only fleetingly.

1) Can I use my preferred full synthetic diesel oil Delo 15w-40 (which is what I use in ALL the rest of my diesel equipment and trucks) instead of the 5w-40 specified in the manual without causing undue damage or reducing fuel economy much, if at all?


2) Though I live in the country and the county roads are shot to hell and my driveway is long and graveled, I RARELY, and only temporarily, use 4x4, simply because Giddyup is my UAV (Urban Assault Vehicle) used for going to town.

I would LOVE to "standardize" the lubrication in the front and rear pumpkins by using EITHER 75w-90 or 80w-90 in BOTH of them … HOPEFULLY without causing real damage to EITHER of them.

2a) Would it really hurt anything to run the heavier 80w-90 lube specified for the front differential in the REAR differential?

2b) Would it really hurt anything to run the slightly thinner 75w-90 specified for the rear in the front differential, given that I ONLY 4x4 temporarily and rarely, if at all?

2c) Is the specified 75w-90 in the rear a GL4 or GL5 ?

2d) Is the specifed 80w-90 in the front a GL4 or GL5 ?


THANKs again for trying to help me sort this out WITHOUT EXACTLY following FSM specs.

 

[seafish]

Evening bump….30 views and no one has any opinions on this controversial subject yet?

 

[duderz7]

I'd run the correct engine oil regardless of convenience. It design to run with that at operating temperature which is relatively the same regardless of ambient temperature. I don't see why you couldn't go either way in the diffs, lube is lube there. Less crucial.

 

[WWDiesel]

Sent you an email.
Many owners use/run 15W40 full synthetic oil in their diesel engines to help provide some additional protection especially in hotter environments.
As to the differential oils, the slightly heavier weight oil provides some additional protection especially if you tow with your Jeep, run larger heavier tires and do 4x4 off roading more frequently. Whatever differential oil you choose, make sure if you have a positive traction Trac-Loc differential in the rear that it is rated for limited slip differentials.

 

[KJowner]

Heavier gear oil should provide better protection for the diff, with a trade off of slightly lower MPG.... in the real world probably very little difference.
Engine oil I'd be a little more careful with, I don't know how fussy the V6 is, some engines with hydraulic lifters need the proper spec oil. I know the diesel isn't too fussy, mine has been running Castrol Enduron for years.

 

[seafish]

Thanks for all who took the time to reply!!!

I will be going with either a full synthetic 15w-40 or full synthetic 5w-40 in the CRD, with the IMPORTANT words being FULL synthetic and NOT a synthetic blend.

I will also use 80w-90 GL5 in BOTH pumpkins with 4 oz LS additive in the rear pumpkin.

And, as previously mentioned, ATF+4 (any licensed brand) in both the AT and TC.

 

[u2slow]

Have used basic bulk 80w90 in both ends of the jeep the since 2012.

Edit: and I don't use any friction modifier with the trac-lok.

 

[seafish]

Edit: and I don't use any friction modifier with the trac-lok.

Just curious why you choose not to ?
Maybe the 80w-90 GL4 you use already has LS additive in it??

 

[u2slow]

Because I want all the grip from a trac-lok that I possibly can get. When it's used up, time to upgrade.

Checked my gear oil. It's super-generic 80W90 with a small footnote it meets GL4 and 5 spec.

 

[CheddarGau]

Time for some 10k and 60k fluid changes.

ATF+4 in the AT and TC is easy, but below are the more controversial questions—

ALL opinions welcome but please no fighting … TIA!!!

I live in a completely temperate climate with outdoor temperatures rarely below 44° and NEVER below 30° and then only fleetingly.

1) Can I use my preferred full synthetic diesel oil Delo 15w-40 (which is what I use in ALL the rest of my diesel equipment and trucks) instead of the 5w-40 specified in the manual without causing undue damage or reducing fuel economy much, if at all?


2) Though I live in the country and the county roads are shot to hell and my driveway is long and graveled, I RARELY, and only temporarily, use 4x4, simply because Giddyup is my UAV (Urban Assault Vehicle) used for going to town.

I would LOVE to "standardize" the lubrication in the front and rear pumpkins by using EITHER 75w-90 or 80w-90 in BOTH of them … HOPEFULLY without causing real damage to EITHER of them.

2a) Would it really hurt anything to run the heavier 80w-90 lube specified for the front differential in the REAR differential?

2b) Would it really hurt anything to run the slightly thinner 75w-90 specified for the rear in the front differential, given that I ONLY 4x4 temporarily and rarely, if at all?

2c) Is the specified 75w-90 in the rear a GL4 or GL5 ?

2d) Is the specifed 80w-90 in the front a GL4 or GL5 ?


THANKs again for trying to help me sort this out WITHOUT EXACTLY following FSM specs.

If you live in cold climate you will want the 5w40. 15w40 might flow too slowly and could give poor lubrication in cold starts conditions and possibly less fuel economy until it warms up. Hot viscosity is the same. Also because diesels have a high pressure fuel pump and the extreme pressures they are under, I rarely suggest people deviate from the recommended oil, unless they are addressing a specific issue.

The gear oil is less of an issue, you can put almost anything in within reason.

 

[seafish]

If you live in cold climate you will want the 5w40.

From the first post—

I live in a completely temperate climate with outdoor temperatures rarely below 44° and NEVER below 30° and then only fleetingly.

 

[CheddarGau]

From the first post—

So you would fall under cold climate. Often there will be a temperature chart listing the temperature range and the appropriate viscosity. Have a look and see if one is available for the engine in service info. It will give you optimum efficiency and lubrication based on the temps . -1 to 6 degrees celcius is fairly cold when it comes to cold starts, even if it isn't often.

 

[seafish]

-1 to 6 degrees celcius is fairly cold

What is this thing called Celcius?

 

[u2slow]

What is this thing called Celcius?

Pretty easy. Water freezes at zero.

 

[CheddarGau]

What is this thing called Celcius?

Kinda like Fahrenheit, but makes sense