Diff Oil

[Ven]

I use Castrol saf-xo. Was cheap from dealer and it's OE.

[wpoll]

Originally Posted by bcredliner

Since diff, transfer case and transmission fluids do just fine for so long I see no reason to use anything other than OE fluid where there is no question that it meets the specs and no risk there it will cause a problem.

but.... not all dealers are created equal and/or use BMW/OEM lubes... around here we use whatever we can get (and that we trust)!

Finding an alternative that actually even mentions the OEM spec is a good start...

[o2bad455]

We're considering a newer X3 for daily use, which would free up our 2004 (E53) X5 4.4i as a weekend tow vehicle (replacing a string of Jeep SUVs from 4.0L, 5.2L and 5.9L, mainly for the beefier trans more than displacement, as the race trailers gained weight over the years). Duties will include hauling a 10K gross trailer with WD hitch at speed for up to half days non-stop at a time, from about -10F to +112F. I've already grabbed the heavier pre-facelift OEM hitch, although the facelift version's holding so far. For drivetrain lubes, I'm either already using or moving to:


N62 4.4L engine: 10W-30 full synthetic


Rear diff: 75-140 full synthetic


Front diff: 75-90 full synthetic


ZF Auto 6-spd: ATF+4 full synthetic (since BMW/Lifeguard6 is apparently just Mercon SP dino oil)


X-Drive transfer case: Need further advice (understood NOT ATF, but is the stock BMW fluid full synthetic or is there anything better?)


I don't want to make this a brand discussion, but any comments on proposed fluid specs greatly appreciated! It has the factory trans fluid cooler. Is that likely sufficient, or should I go bigger? Any other coolers needed for summer towing? Thanks in advance!

[Bdc101]

What's your trailer weigh fully loaded? You know the V8s were rated either 5,500 or 6,000lbs towing capacity, right?



I tow a camper that weighs about 4,000lbs fully loaded throughout the summers in up to about 105F, and it handles it just fine with a WD hitch. We typically have the AC blasting in the summer heat while climbing 8% grades and recently got two SUPs to put on top of the car too. Sometimes I will be at WOT in 3rd or 4th for 15 minutes straight without lifting in order to get over a pass. This is my third summer doing this routine and I've never had any sort of failure.



I use some sort of synthetic oil, usually 5w40 or 10w40, with Valvoline full synthetic diff oil and trans fluid. I don't know what the N62 oil spec is but I would err on the side of heavier oil instead of thinner, since your oil will generally be hotter when towing than normal operation.



I do not have an auto or a V8, but that's my experience and it's worth exactly what you paid for it.

[bcredliner]

The type of lubricant is part of the design criteria of driveline components. I use only the recommended OE lubricant for transmission, diffs and the transfer case for that reason. Better lubricants are not necessarily better for a component. Engine oil is an exception and I don't want to get into that either. As far as engine oil, any good brand with same specs and weight changed frequently will be fine.

I would be as or more concerned with the suspension, tires and brakes.. I would refresh the suspension and go to heavy duty shocks and struts if you haven't already. Tires? I don't do any towing with my X5 so don't know what is out there but I would want them on wider rims than stock. I would go to bigger brakes.

That said, I think you are asking for trouble using your X5 in the conditions you mentioned. You need a vehicle that is built with towing in mind which would include in the conditions you mention. Otherwise, my guess is you will be very late for some of your destinations.

[o2bad455]

Thanks for the tips so far! Still seeking: "X-Drive transfer case: Need further advice (understood NOT ATF, but is the stock BMW fluid full synthetic or is there anything better?)"

Originally Posted by Bdc101

What's your trailer weigh fully loaded? You know the V8s were rated either 5,500 or 6,000lbs towing capacity, right?

Trailer gross is twice that rating, but it's rarely THAT fully loaded. I chose SUVs (choose SAV) over trucks for various reasons beyond the scope of this thread. Any tow vehicle's rating is necessarily determined by its weakest link.

My prior non-BMW SUV towing failures have included one (1) heat-related mechanical engine failure, one (1) heat-related rear diff failure, two (2) AWD transfer case failures, and three (3) automatic transmisssion failures (one apparently from heat alone, one when a belt took out an ATF cooler line, and one when the transfer case failed putting sudden additional load into the trans while in OD). I've dealt with the usual issues including tire blowouts at speed, but only because everything else was matched to the task. I've also heard of, but never myself encountered, a front diff failure.

I presume the pre-facelift E53 was probably limited by it's transmission's max torque, the post-facelift by it's lighter duty hitch, and anything other than a 4.8 by its brakes. Taking the best of each, plus heavy-duty shocks and brake components, an oversized weight-distributing hitch (I think this is key), and a quality aftermarket trailer brake controller, I'm fairly certain that the next weakest link would be some part of the drivetrain. Hence, my quest for the best full-synthetic lubes for every component (and potentially additional coolers but only as needed). Make sense?

[Clavurion]

Originally Posted by o2bad455

Still seeking: "X-Drive transfer case: Need further advice (understood NOT ATF, but is the stock BMW fluid full synthetic or is there anything better?)"

Can't say there there is any compatible oil clearly better than OEM. Either get original BMW DTF-1 or similar specs like Ravenol TF-0870.

https://www.ravenolamerica.com/gear-...venol-tf-0870/

[o2bad455]

Originally Posted by Clavurion

Can't say there there is any compatible oil clearly better than OEM. Either get original BMW DTF-1 or similar specs like Ravenol TF-0870.

https://www.ravenolamerica.com/gear-...venol-tf-0870/

That looks like a match, thanks! The page you linked says it's "fully synthetic" but available only at BlauParts and Amazon. I just checked Amazon, but only found Rock Oil (Gearaxl), Shell, AC Delco, and BMW Group brands stating "TF-0870". The only Ravenol brand stated "DTF-1". No idea if they're the same. Some mentioned "synthetic", but not "fully synthetic" so they might be dino/synth blends.

I then found this advertisement about "TF-0870" on BimmerWorld: "This fluid was previously called TF0870 but has been replaced with a re-branded version called DTF-1. Note that this fluid is for the transfer case manufactured by ATC and used in 2003+ xDrive models. AWD models prior to 2003 use a NV transfer case which takes standard ATF Dexron III oil. This is xDrive DTF-1 fluid manufactured by Rein Automotive - an original supplier to BMW for many engine components." I noticed that the Rein ad doesn't even mention if it's synthetic, much less fully synthetic. Moreover, when I zoomed in on a low-res pic of the container, it clearly said "first fill" which, at least in my experience, is often dino oil for break-in purposes.

BlauParts does list "Ravenol Transfer Case Fluid TF-0870 / DTF-1 1L" and also says it's "fully syhthetic", so we'll probably go with that. I still wish there was something more readily available locally (in North America for me; such as Redline, Valvoline, or the like).

EDIT #1: The correct Ravenol sku is J1C1125 for the fully synthetic ATC X-Drive transfer case oil, regardless of whether it's being called TF-0870 or DTF-1.

EDIT #2: The Rock Oil gearaxl TF-0870 (sku: IYK500010) is a fully synthetic spec'd for Land Rovers of same vintage, which I believe had the same ATC transfer cases (since BMW owned Land Rover at the time). It seems to be geared towards high-performance applications, it's surprisingly more readily available from US sources, but more expensive unless buying 2 at a time (sku: IYK500010K2; perhaps some Land Rovers needed 2 liters per vehicle?). It also meets BMW specs for the ATC 500 transfer case in our 2004 E53-LCI as well as the ATC 400 in our 2008 E83-LCI. We've just ordered this.

EDIT #3: I just found this: Redline MT-LV 70W/75W GL-4 Gear Oil. Redline's online description says "Popular in ... BMW X-Drive and other transfer cases calling for Shell TF0870." A local speed shop might even have it in stock!

[jbfrancis3]

Originally Posted by oldskewel

If "diff oil" means the oil to put in your differentials, one of the most important things to be sure of is that it is GL-5 (and not GL-4, which would more commonly be used in a manual transmission).

[removed my incorrect statement]

Still correct: For the NV transfer case [non X-Drive], Dexron III ATF is the spec while D4 ATF is a common and accepted replacement, often providing GL-4 level.

[o2bad455]

Originally Posted by oldskewel
If "diff oil" means the oil to put in your differentials, one of the most important things to be sure of is that it is GL-5 (and not GL-4, which would more commonly be used in a manual transmission).

I agree with oldskewel for the front and rear hypoid differentials.

Originally Posted by jbfrancis3

... For the NV transfer case [non X-Drive], Dexron III ATF is the spec while D4 ATF is a common and accepted replacement, often providing GL-4 level.

I also agree with jbfrancis3 for the transfer cases, which may include a non-hypoid center differential.

I guess we should clear up some confusion. When I was seaching for transfer case info, I found as much info calling it a "front diff" which is clearly wrong. If any type of diff, a non-locked transfer case may include a center differential, but non-hypoid (so non-EP).

Our front and rear differentials definitely require a GL-5 EP (Extreme Pressure) lube. The requirements for the X-Drive ATC transfer cases were where the lack of info was, and it looks like for at least the E53 (ATC 500) and E70 (ATC 700), those take some sort of GL-4, perhaps with special non-EP additives. I imagine the EP additives in a GL-5 might be very bad news for these transfer cases.

Bottom line: GL-5 for front and rear diffs, some type of GL-4 for the X-Drive transfer cases (at least ATC 400, ATC 500 and ATC 700 where TF-0870 was originally spec'd before DTF-1 may have evolved), and ATF for the NV transfer cases.