Front Diff oil change

jinstall · **Posted:** Wed Sep 28, 2011 2:19 pm

Also explains why the OEM requirement is 2 different types of fluid as well.

tjkj2002 · **Posted:** Wed Sep 28, 2011 8:10 pm

jinstall wrote:

Also explains why the OEM requirement is 2 different types of fluid as well.

There's only one for my year of KJ's front D30A,and that is dino 80w-90.It's right in the owners manual.

ATXKJ · **Posted:** Wed Sep 28, 2011 8:50 pm

Actually Tom
that would be wrong - somewhere there's an SAE definition for 'cling' and synthethic's are better at it than Dino (it was one of the big advertising points a few years back). And while you might understand the logic on both sides - but when you're debating whether one is better than another - you can't both be right.

Actually I called Currie and asked why they recommend synthetic.... and I don't think they've ever been trained in 5-Why's because the 2nd and 3rd whys -the answers were less definitive - so I stopped there - however.

They support a lot of racing
If a gearset fails - they get it back and do a Failure analysis - that includes sending parts to an outside lab for analysis.
They consistently have fails on synthetic.
it seems like the gears/bearings are overheating - it did not seem that the oil was breaking down - just the gears were getting hotter.
they didn't really look at the next why - but the comment was that either the oil was helping retain the heat - or that it was behaving as a lighter weight oil.

At that point - their answer was don't use synthetics - and they won't warranty any diff that has used synthetics.

They have not published any papers or reports (and it wasn't clear that they even had internal documents - maybe a couple of emails)

So from an Engineering standpoint - they still have a couple more levels of why that they never got to.
However from their production standpoint - they're comfortable with a complete ban.

I would point out - these were racing fails - but that's Currie specialty - differentials/axles that can take serious abuse and survive.

and I do feel like - that if Mobil came in with money & engineers - they'd figure the last couple of why's - and fix the issue - however i don't see that happening.

So if you're stressing the Diff - I'd recommend a quality Dino oil - changed regularly.

tjkj2002 · **Posted:** Wed Sep 28, 2011 8:59 pm

ATXKJ wrote:

Actually Tom
that would be wrong - somewhere there's an SAE definition for 'cling' and synthethic's are better at it than Dino (it was one of the big advertising points a few years back). And while you might understand the logic on both sides - but when you're debating whether one is better than another - you can't both be right.

Actually I called Currie and asked why they recommend synthetic.... and I don't think they've ever been trained in 5-Why's because the 2nd and 3rd whys -the answers were less definitive - so I stopped there - however.

They support a lot of racing
If a gearset fails - they get it back and do a Failure analysis - that includes sending parts to an outside lab for analysis.
They consistently have fails on synthetic.
it seems like the gears/bearings are overheating - it did not seem that the oil was breaking down - just the gears were getting hotter.
they didn't really look at the next why - but the comment was that either the oil was helping retain the heat - or that it was behaving as a lighter weight oil.

At that point - their answer was don't use synthetics - and they won't warranty any diff that has used synthetics.

They have not published any papers or reports (and it wasn't clear that they even had internal documents - maybe a couple of emails)

So from an Engineering standpoint - they still have a couple more levels of why that they never got to.
However from their production standpoint - they're comfortable with a complete ban.

I would point out - these were racing fails - but that's Currie specialty - differentials/axles that can take serious abuse and survive.

and I do feel like - that if Mobil came in with money & engineers - they'd figure the last couple of why's - and fix the issue - however i don't see that happening.

So if you're stressing the Diff - I'd recommend a quality Dino oil - changed regularly.

See real world testing by many independant testers(poeple who use Currie rearends) is much better then some $3million dollar test paid by a oil company and ran to show there stuff being the best.

onthehunt · **Posted:** Wed Sep 28, 2011 10:31 pm

In my line of work I have found fluid level and purity to be MUCH more important than syn vs dino.... but I hate to to interrupt another useless syn vs dino oil thread. Please continue.

DIESELIB · **Posted:** Thu Sep 29, 2011 1:26 pm

ATXKJ wrote:

Actually Tom
that would be wrong - somewhere there's an SAE definition for 'cling' and synthethic's are better at it than Dino (it was one of the big advertising points a few years back). And while you might understand the logic on both sides - but when you're debating whether one is better than another - you can't both be right.

Actually I called Currie and asked why they recommend synthetic.... and I don't think they've ever been trained in 5-Why's because the 2nd and 3rd whys -the answers were less definitive - so I stopped there - however.

They support a lot of racing
If a gearset fails - they get it back and do a Failure analysis - that includes sending parts to an outside lab for analysis.
They consistently have fails on synthetic.
it seems like the gears/bearings are overheating - it did not seem that the oil was breaking down - just the gears were getting hotter.
they didn't really look at the next why - but the comment was that either the oil was helping retain the heat - or that it was behaving as a lighter weight oil.

At that point - their answer was don't use synthetics - and they won't warranty any diff that has used synthetics.

They have not published any papers or reports (and it wasn't clear that they even had internal documents - maybe a couple of emails)

So from an Engineering standpoint - they still have a couple more levels of why that they never got to.
However from their production standpoint - they're comfortable with a complete ban.

I would point out - these were racing fails - but that's Currie specialty - differentials/axles that can take serious abuse and survive.

and I do feel like - that if Mobil came in with money & engineers - they'd figure the last couple of why's - and fix the issue - however i don't see that happening.

So if you're stressing the Diff - I'd recommend a quality Dino oil - changed regularly.

The cling tests that I'm refering to were performed on various set-ups and done at various temperatures. In ALMOST all the tests conducted, good ole DINO lube scored a higher (not by much) percentage of sustainability on a part when left for a specified period of time....meaning more of a coating still remained after a specified amount of time than it's synthetic counterpart. HOWEVER it was the SYNTHETIC fluid that scored a better grade in overall performance due to its superior lubricating properties as well as the reduced friction loss. Basically stated in the rock crawler senario where there's insuffficient speed generated to properly splash the parts with the lube....or because the fluid is simply unavailable due to an adverse angle where the fluid is all accumulated in an axle tube...the DINO had a SLIGHT advantage. Being that my jeep will NOT be used as a rock crawler or for any adverse driving conditions I have no problem using EITHER type.... On another note....my other 2 trucks both have SYNTHETIC fluid in all their diffs....and I have noticed a small benefit of SLIGHTLY better mileage and a "cleaner" overall appearance of the internal parts since switching and I'll most likely follow through with my Jeep when the time comes....
Tom

tjkj2002 · **Posted:** Thu Sep 29, 2011 4:30 pm

DIESELIB wrote:

..my other 2 trucks both have SYNTHETIC fluid in all their diffs....and I have noticed a small benefit of SLIGHTLY better mileage

Bingo!!!!!!!!!!!

The only reason synthetic gear oil is used today,to increase mpg's but at the cost of diff life.

DIESELIB · **Posted:** Fri Sep 30, 2011 11:37 am

TJKJ2002: If you notice I DID give the synthetic credit for a better overall appearance too....lol :wink:

I'm a firm believer that as long as you follow proper change intervals, DINO will be just fine......but if you want to get the most mileage/best possible protection for TYPICAL driving scenarios then the SYNTHETIC will get the nod...

jinstall · **Posted:** Fri Sep 30, 2011 5:09 pm

tjkj2002 wrote:

jinstall wrote:

Also explains why the OEM requirement is 2 different types of fluid as well.

There's only one for my year of KJ's front D30A,and that is dino 80w-90.It's right in the owners manual.

Front lists 1 the rear lists 2 from my owners manual.

cgass · **Posted:** Fri Sep 30, 2011 6:24 pm

Talked to my Amsoil dealer today, they don't recommend their oil for lockers and make an additive for LSD's. My dealer said he still wouldn't use it in an LSD though

Front Diff oil change

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