Dino vs syunthetic in SUV Differentials?

[ryan2022]

Some axle manufacturers are too chicken to admit that they sometimes ship a garbage gear set. When they hear that the owner used a synthetic, the ol' Neanderthal mentality kicks in at the manufacturer and the word 'synthetic' is easy to blame. Show me the proof?

[/quote]

That is probably the best and funniest way I've heard the syn vs dino gear lube summed up.

 

[wtd]

I'm not sold on synthetics in the diffs. On my 98 K1500 which I bought new, I had the rear diff fluid changed per the owner's manual at the first oil change. At 20,000 miles I changed the front and rear diff to Mobil 1 diff fluid. I changed them again at about 40,000 miles with Mobil 1. At about 55,000 miles I started getting some whining noise which I wasn't sure where it was coming from. At about 75,000 miles I had to have the pinion and carrier bearings replaced in the rear because they were very worn and causing a high pitched whine. After that I quit using synthetics in the diffs and just use conventional fluid. Of course I now have some type of noise in the front end and have had for awhile. Mobil 1 sure didn't protect the bearings in the rear diff very well and this is on a truck that hardly pulled or carried anything. I'm just not a synthetic fan anymore and I used synthetics for years. Synthetics just haven't seemed to perform very well in my vehicles, especially not for what they cost.

Wayne

 

[Ben99GT]

I've had great luck with synthetics in the rear axle, mostly Redline though.

 

[wirelessF]

The way the Nissan Titan's diff is set up it must be running some high end diff sauce in there. The rear end looks small to handle the 5.6L engine compared to Ford and Toyota's rear ends.

 

[unDummy]

The Nissan Titan uses a Dana44 rearend which is grossly undersized for the capabilities of the vehicle. Originally, Nissan used a 90wt and a plain diff cover on the Titan. After blowing up plenty of rearends, Nissans upgraded to a 140wt gear oil along with a fancy cooled fin'd diff cover. Enough said about OE engineering and testing. The real world proved that OE testing was inadequate 'again'. And, every automaker seems to have similar issues. Makes you wonder who's doing the testing?

When possible, IMO, everyone should upgrade to a synthetic. And, if any issues are known for the 'end type, then going up a grade or 2 thicker should be considered. Also, adjust as needed for the fluid type/weight/interval for your vehicles usage.

 

[tdi-rick]

unDummy is right, I can't believe this 'argument' is still going round and round ??

Twenty years ago the only way to make crown wheel and pinions last in race transaxles by Hewland and XTrac used in the then Formula Holden here, the then F3000 internationally, Champ Car and F1 was to use the syn lubes, eg Neo RHD, Motul Gear300, Elf and Ams.
Neo and Amsoil were the factory recommendations by Reynard in their F3000's and Champ Cars, IIRC they used Hewland internals. X-Trac, who supplied the bulk of the F1 teams, quite a few of the then 2 litre Super Tourers, most WRC cars and probably half the Sports Car fields recommended Neo 75W-90 RHD, Hewland recommended Neo or Ams.
By doing this teams went from replacing CWP's every meeting in F3000 and F1 to doing an entire season on a diff.

Yes, there are a some excellent conventional diff oils that outperform 'average' synthetics, Texaco's Boron additised diff lubes and LE and Swepco's stuff comes to mind, but to claim that any old conventional oil outperforms a good syn ??

Read some of Doug Hillary's posts re his experience switching to syn flids in the big rigs diffs, anything by Molakule and Bruce381.

On a rig used a lot off road and that does a lot of water/creek/river crossings I'd use conventional diff oils purely due to possibility of water contamination and the need to change/flush fluids regularly, otherwise it's syn all the way for me.

We've clocked up 310,000km on the diffs in our Nissan Patrol tray back and the rear one is Nissan's H260 diff. This is around the size of a Dana 60 but with a lift out centre and with a plate LSD inside and it's as quiet and tight as new. This vehicle has been used for most of its life towing horses and is currently loaded up with a constant 600kg or so of my work gear, so it hasn't been babied.
It's been fed a diet of Castrols SAF-XA, an 80W(nee 75W)-140 PAO/ester LSD fluid for the majority of it's life, from the factory it came with a straight SAE 140 fluid.

 

[tdi-rick]

Originally Posted By: wtd
I'm not sold on synthetics in the diffs.

Synthetics just haven't seemed to perform very well in my vehicles, especially not for what they cost.

Wayne


Wayne, I'd be suggesting poor set-up from the factory or sub standard bearings rather than the lube used.

Mid nineties on GM Holden Commodore rear ends here are notorious for needing new carrier and pinion bearings at just over 100,000km/60,000 miles (or just out of warranty)
Two of my mates have had this problem with their vehicles, and the diff specialists blame the bearings fitted from the factory.