ATF in manual gearbox? 1

[PEW]

One of the two helicopters I fly for a living (both are Sikorsky S-76s) uses Mobil 254 (primarily a turbine engine oil) in the main, intermediate and tail rotor gearboxes.

The other heli uses ATF in the gearboxes, (Mobil 254 again in the engines). Both oils have similar viscosities judging by how they pour when we top up.

A while back a colleague's car needed a new driveshaft CV joint and he was helped out by a friendly helicopter engineer. After completing the work, they put Mobil 254 in the gearbox as it was "freely available". It is still going strong as far as I know.

I hav almost finished rebuilding the tranmission of my little trials car, which has just an 850cc engine. Power losses through transmission drag are a significant percentage of the total engine power available (only about 50 bhp at the flywheel estimated), especially as I just have changed to a small van axle for extra strength.

All this has got me thinking about suitability of oil types, viscosities, etc.

It makes sense to use as light an oil as possible in the manual gearbox and (hypoid) rear axle. However, the manufacturers' recommendations are 80w in the gearbox and 90w in the rear axle. I have previously been using a semi-synthetic 75/90w.

Could I use ATF without compromising longevity or reliability? (Mobil 254 is actually extremely expensive so I won't be using that).

For years I thought that ATF was only meant to be used in automatic boxes, but in view of the helicopter using it, is this not so critical?

BTW, I am aware of the requirement for a sulphur additive or similar to reduce wear due to the higher contact loads and "sliding" motion in a hypoid axle rather than in a straight cut gear set.

 

[evelrod]

ATF, in general , works well in automotive standard gearboxes. I was concerned,as you are, when I first switched in 1967!!! 28 years in several street and racing Lotus Cortinas and Elan gearboxes, Leeson, Jack Knight, Ford, all worked perfectly and never had a problem. The gearboxes ran cooler and shifted smoother but they WERE a bit noisier in normal operation. Ford used ATF as standard OEM in my 1983 Thunderbird T-Coupe and I had over 200,000 miles when I traded it in 1995. There are extensive threads dealing with all this but, I don't have the patience to look them up. I am sure the folks out there that will speak to the added leakage problem but, in all honesty, I just have not had that problem. Several mfgrs. aside Ford are currently using ATF as standard in manual transmissions. I am even contemplating using ATF synthetic in the gearbox of my 1948 Norton at next service to see if it will smooth up the shift.

Rod

 

[jons999]

So ATF is safe to use in any manual transmission? The trans in my truck could use some new synchros and it's almost impossible to shift when cold, especially into 2nd. In the winter time i usually shift from 1st to 3rd until i've driven 3 or 4 miles and the trans has warmed up. I was going to flush it out and put synthetic gear oil in but i'm wondering if atf will work better?? I know most FWD vehicles are using ATF in the differentials. I believe the trans is an AX-15, used by both Toyota and Dodge.

-Jon

 

[Peter7307]

PEW,
From a user perspective: I have Dexron III in my Borg Warner T5 manual gearbox fitted to a 3.8 litre V6 with 478,000 Klms (about 250,000 miles) and have had no problems to date. It is changed every 50,000 klms.
The change to ATF came on the advice from Borg Warner Australia who confimed the suitability.
Practically there is no difference for the driver ; the cold shifting is smooth and notch free and the 'box is as quiet as it was previously.
Hope this is of some help.
Cheers, Pete.

 

[PEW]

Thanks for the replies.

It seems that as long as ATF can be kept in the box rather than on the floor, it should be OK.

Another thing that occurred to me is the fact that my gearbox has brass / bronze material synchro cones. I have read that EP (sulphur based) additives are actually bad for these metals but the manufacturer recommends an EP oil. Doesn't make sense to me, in the past I have had to rebuild a couple of gearboxes on cars I owned purely because the synchros were bad.

Paul W

 

[Slowzuki]

The local refinery / lube supplier put on a seminar recently. He mentioned that the only reason their company still produced EP greases (may apply to other lubes) is due to old specifications and people designing using old references and specing EP. The particles have been shown to increase wear when overloaded. In particular older "moly" lubes which use chrome-alloy particles are the worst.

Ken

 

[romke]

EP additives can indeed wear away synchromesh materials at a faster rate as wished for. another by-product of EP-additives may actually be friction reduction, which may lead to longer shifting times and possibly overheating of synchros. standard gearbox oils do use a certain amount of EP additives to prevent tooth wear - the art in making a gear oil is to strike the right balance between wear protection of gear surfaces while at the same time not compromising the synchromeshes. usually this is achieved by using less EP additive (API GL-4 level) whereas backaxles usually contain twice as much EP-additives. The latter products should be avoided in gearboxes unless explicitly required by the manufacturer.

 

[notts]

In my experience, it is better to use ATF for synchroniser performance in manual transmission in general. Especially it is good for shifting in cold weather. But it won't be good for speed gear durability since lower viscosity will make the oil film thickness thinner in the gear mesh. Also, the EP (sulphur additives) is harmful to the durability of bronze synchroniser rings as many folks have pointed, which ATF may have. But many types of oils for manual transmission have sulphur based additives as well.

But we have to know that helical gears in automatic transmissions last enough for its life in ATF.

In conclusion, ATF should not be a siginificant problem in manual transmission.

 

[stevo440]

So is it safe to say that instead of the 10w-30/10w-40 motor oil recommended for use in my Honda Civic 1.5L manual gear box, that A/T fluid (Dexron, Mercon, etc) which one or are they all OK? (Synthetic or Non-Syn or both). Also, if the above oils are recommended is it also safe to say that 5w-30, 5w-20, 0w-30 and 0w-20 motor oils are OK alternatives. (Synthetic, Non, or both)

Thanks
Steve

 

[widman]

Two critical issues: Viscosity and Additives. Many manual transmissions are designed for ATF. These normally have wider conical brass sincronizers and cannot displace a 80w90 gear oil (Ford/Mazda is in this group). But if you reduce the viscosity of the oil below the designed point, you lose hydrodinamic lubricacion and cause higher wear. Each transmission is designed for specific weights or ranges. I know a company that standardized their transmission fluid at 80w90 in their fleet of trucks between Volvo and Scania. The Volvo needs 80w90 while the Scania needs 85w140. At 240,000 kilometros the Scanias are showing severe wear and one failed.
Additives: The standard Sulfur/Phosforous package used for EP can be detrimental to bronze sincronizers as mentioned, but this can be avoided with Inorganic Borate EP additives such as those used in Chevron's Delo Gear that do not form chemical bonds with the soft metals and then peel off.

 

[idano]

PULLLEASEEEE...

use the FACTORY recommended lubricant in whatever it is you are lubricating.

Example.....dont ever ever use automatic trans fluid in a GM/Saginaw power steering pump or box....use the correct GM power steering fluid.

Especially in transfer cases made in the 80's and later in 4WD trucks it is IMPERITIVE that you use the factory fill.

Now this is a litle less important in pre 70's vehicles that just specify "engine oil" or hypoid gear oil".

In some standard transmisions there is specified certain lubricants other than hypoid gear oil or motor oil.....use what the manufacturer specifys...this is extremely critical for LONG life....ZF, Borg Warner 5 and 6 speeds especially.

Auto trans need their specified fluid....DexronIII, Honda, Toyota all have a different and specific addative package.....due to the higher usage of ATF in Dexron and Mercon, other brands than factory fill are made to these exact specifications and would be acceptable.

 

[evelrod]

Well, idano, aside many OEM's recommending ATF and the fact that I have had zero problems using it in the above mentioned gearboxes---when in search of improved performance, risk nothing, gain nothing! If you just follow the herd, take a peek at the best view you can expect to see !
Welcome to the forums.

Rod

 

[nostrayvoltage]

idano or others

Can you provide any insight into the correct/acceptable lubricant for the ZF6 transmission as used in 1996 Corvette?

GM speicifies a special 5W30 lubricant, which no one else has available as equivelent. ZF now says to use Castrol TWS 10W60.

What gives????

no_stray_voltage@yahoo.com

 

[yoyo133]

For what it's worth some outboards, in the 60's and 70's, had electric shift gearcases (essentially a differential) in which the standard 80w90 was too heavy for the shift solenoids and the hydraulic mechanism they controlled. The outboard manufacturers came up with a Type C oil for those gearcases which is probably about a 5w20 to replace the usual hypoid oil and it works just fine.
I also replaced gearbox and differential oil with ATF in a mini-stock Ford Capri race car (much to the owners horror) strictly as a horsepower saver and never had a problem...we won quite a few races as well!!!

 

[Tmoose]

"GM speicifies ....5W30 lubricant, which no one else has available as equivelent. ZF now says to use Castrol TWS 10W60.

These guys say say they analyzed the full synthetic 10W60 and the "60" got torn up ~ 40 pretty quick (100 miles) and by 10,000 miles was in the 30s. And was so full of suspended bronze they recommend that as the change interval

http://www.zfdoc.com/faq.htm

----------------------------------------------------

At 100 C here some viscosities (in Cst) off the Internet-
ATF Dex III = 8
5W30 = 11
10W-30 = 11
10E-40 = 15
10W-50 = 19
did not find what "60" is like

 

[nostrayvoltage]

Tmoose

Thanks for your reply regarding ZF6 lubricant.....The question still remains as to alternate lubricants...for example what about MobilOne in 5W30 vs the GM5W30 special lub or what about Mobil1 in 15W50 vs the Castrol 10W60

Seems to be issues regarding viscosity, change intervals, and additives(type of oil).....

I am not a lubricant engineer, but more interested as a Corvette owner as to proper lubricant for my transmission.

Seems to me there should be a basis as to which is correct..



no_stray_voltage@yahoo.com

 

[Tmoose]

It seems like ZF has decided that the CAstrol IS the right one. I generally stick with manufacturer's recommendations. I figure they at least get to see a lot of the broken ones.

According to this - Around 1998 ZF, not GM, was rebuilding them. The following is from some archived message board that Google found in 14 seconds.

http://www.5speeds.com/archive/27.html

Sounded pertinent, but maybe too old.
> .....now seeing alot of broken 6 speeds and problems in 5 > year and older vettes. There are NO SERVICE PARTS offered > from GM for these transmissions. There never was. I > personally will never purchase any car from any company >that doesn't offer service parts for assemblies such as >engine or transmissions. GM just discontinued service >parts for the 4+3 overdrive and we are busy making alot of >these components. The current 6 speed repair proceduce is >the unit is removed and validated as a Corvette 6 speed >then boxed and shipped to ZF North America. Minimum cost >to inspect the unit is $500 plus freight. Average repair >costs are $2500.00.

-----------------------------
Specifically re: Mobil One - here's something from the Yahoo Grandsport group back in August 2003

http://autos.groups.yahoo.com/group/grandsport/message/715?source=1

There is a reference from ZFdoc. Here's a piece of it.
> I don't know why or where anyone is using Mobile-l
> in these transmissions. Do you have any idea where
> the suggestion originated from? I'm curious to know.
> 4 out of 4 units that I rebuilt which had Mobile-1 in them had
> signs of galling on the synchronizers.

Later he mentions several other lubes. I guess those are or were approved, whether by him or GM. Mobil 1 is good stuff. I could only guess why it would cause/allow a problem, when when some conventional 5W-30 works OK for 10k miles.

> The factory fill 5W-30 (GM P/N 1052931) is good for 10K mile
> intervals.
> Redline MTL is good for 20K mile intervals between changes.
> Castrol RS 10W-60 (BMW P/N 07 51 0 009 420) is good for 10K mile
> intervals.
> Even though the Castrol has to be changed twice as often as the MTL,
> I still prefer it's performance above the rest.

---------------------
Have you been here?

http://www.zfdoc.com/techinfo.htm

He has a drill he recommends as practice for "power shifting" a ZF equipped Corvette. Just the kind of thing I would have practiced every day in high school, undoubtably to the cruel enjoyment of my fellow students.

 

[nostrayvoltage]

I am familiar with

http://www.zfdoc.com

What is there that is so different about the ZF6 that it requires such a special lubricant???

The Castrol product is only available at BMW dealers at about $9 per quart.

My Corvette at just a little over 30K miles still has the factory fill. Just trying to get a better basis for selecting the refill. Do I believe GM or ZF or ????

no_stray_voltage@yahoo.com

 

[Tmoose]

I did not find a recent reference to GM's spec on line.
What do they say now? I'm more than half expecting they'll go along with the ZF recommendation.

According to ZF DOc you're way overdue for an oil change no matter which one of his referenced oils you're using.

I think its curious ZFDoc says the oil change limiting factor is suspended bronze particles, and also reported the Mobil-1 damage is synchronizer galling (maybe the steel cones, not specifically the bronze synchro rings).

There are not many bronze alloys I consider my friend.

 

[nostrayvoltage]

Actually ZFDOC gives both lubicants as alternatives & I am pretty sure GM still stands by its original recommendation.

http://www.zfdoc.com/techinfo.htm

Still do not understand which is best or why other lubricants are not acceptable. Is bronze unique to the ZF6??


no_stray_voltage@yahoo.com