Bubbles/foam in gearbox oil ?

[Popsy]

Hi guys,

Today I drained the gearbox oil in the Smart (basically a Mitsubishi Colt rebadged), to fix/change the selector, and the oil was full of bubbles, almost foamy. It's the first time I see a so much «foamy» oil, do you think it is normal ? Arent't gearbox oils packed with antifoam additives?
Oil is Mobil 1 SHC 75W90, and I was planning to reuse it since it is faily new.

After a few hours in a clean bottle it has les bubbles but still has some foam.

 

[stchman]

Since the gear oil is already drained, just get some new.

 

[MolaKule]

Anti-foam doesn't mean "No Bubbles."

What is means is that the foam inhibitor, a silicone polymer, causes bubbles to burst faster.

 

[Popsy]

Anti-foam doesn't appear very efficient in this oil, it took a long time for the bubbles to burst....
The question is, is this normal? Previous oil (unknown, probably factory fill) didn't react like that...and the oil was drained cold (car off for several hours), since I was planning to filter and reuse the oil. Maybe hot the additive would have been more efficient?

Also it is the only gearbox oil I have in my stash, and it Is the oil I put in all the cars in my sig except the Barchetta

Should I try something else? I'd rather not since I have 5 liters left.

Edit: good news is the selector won't need replacement

 

[MolaKule]

I guess my question is, why are you using a thick, heavy duty truck transmission fluid when there are dedicated MTF's that will provide better cold temperature shifting and has friction modifiers just for synchromeshes?

Quote:
Mobilube 1 SHC 75W-90 meets or exceeds the requirements of the API Service MT-1/GL-4/GL-5 gear oil service classifications.


Two dedicated fluids that come to mind are:

Redline MT-90

http://www.redlineoil.com/product.aspx?pid=46&pcid=7

and Amsoil MTG:

http://www.amsoil.com/shop/by-product/tr.../?code=MTGQT-EA

 

[zeng]

Originally Posted By: Popsy
Anti-foam doesn't appear very efficient in this oil, it took a long time for the bubbles to burst....
The question is, is this normal? Previous oil (unknown, probably factory fill) didn't react like that...and the oil was drained cold (car off for several hours), since I was planning to filter and reuse the oil.



Tend to agree with your line of thought.
The foaming you described certainly appears abnormal.I would first ensure low fluid level is ruled out before looking into other possibilities.

 

[Ducman]

Originally Posted By: zeng
Originally Posted By: Popsy
Anti-foam doesn't appear very efficient in this oil, it took a long time for the bubbles to burst....
The question is, is this normal? Previous oil (unknown, probably factory fill) didn't react like that...and the oil was drained cold (car off for several hours), since I was planning to filter and reuse the oil.



Tend to agree with your line of thought.
The foaming you described certainly appears abnormal.I would first ensure low fluid level is ruled out before looking into other possibilities.

It's not abnormal.
The issue needs to be put into some sort of perspective.

Some very good oils will still form small uniform sized bubbles that only sit on the very top of the oil film and do not pose a threat to the longevity of the unit.
The bubbles are just large enough to harmlessly float readily to the top of the oil bath regardless of what's going on inside the assembly, and remain on the very top of the oil until they burst relatively quickly and the condition doesn't get out of control.

This is opposed to catastrophic "foaming", where the oil has a distribution of different sized bubbles emulsified throughout the depth of the oil bath to varying degrees(depending upon operating conditions) within the assembly.
The different sized bubbles can be quite microscopic in size and remain suspended in the main body of the lube which get distributed throughout critical areas.
This ultimately leads to a breakdown of the lubricating film where we absolutely don't want it to occur.

To summarise.
In real terms, there is an enormous difference between the two conditions.
The former is generally not problematic.
The later is potentially catastrophic under any conditions.

If in doubt, simply try another brand of oil.

 

[Popsy]

The bubbles appeared to be uniform in size, and were floating on top. So maybe that's not so bad? Should have taken pictures!

Originally Posted By: MolaKule
I guess my question is, why are you using a thick, heavy duty truck transmission fluid when there are dedicated MTF's that will provide better cold temperature shifting and has friction modifiers just for synchromeshes?

Well, I have no access to Amsoil products, and very limited to Red Line (which are crazy expensive here). Mobil 1 SHC 75W90 had the right specs, was easily available, and cheap. Plus it was from a supposedly good oil company. The gearbox operation was good, certainly smoother than with the previous fluid, and the selector failure (more seizing than failure) is a well known and repetitive problem on these gearboxes

Mobil fluid was not marketed as hd truck transmission fluid, just basic universal GL4/GL5 fluid

Originally Posted By: Zeng
Tend to agree with your line of thought.
The foaming you described certainly appears abnormal.I would first ensure low fluid level is ruled out before looking into other possibilities.

You can rule out low fluid level

Maybe it is just some incompatibility with previous fill? Is it even possible? I don't know what is the FF in these Smart, maybe some Mobil fluid? Lol

 

[Lubener]

Could have a small amount of water contamination. Should not be foamy.

 

[Jetronic]

the bubbles are more apparent when the oil is cold (high viscosity)

put some oil in a bottle, heat it in a water bath, then shake the bottle.

 

[GiveMeAVowel]

Originally Posted By: Popsy

Well, I have no access to Amsoil products, and very limited to Red Line (which are crazy expensive here). Mobil 1 SHC 75W90 had the right specs, was easily available, and cheap. Plus it was from a supposedly good oil company. The gearbox operation was good, certainly smoother than with the previous fluid, and the selector failure (more seizing than failure) is a well known and repetitive problem on these gearboxes

Mobil fluid was not marketed as hd truck transmission fluid, just basic universal GL4/GL5 fluid

It's unlikely that your model uses GL-5 spec fluid I would bet it is spec for GL-4 ONLY.

How about Castrol Syntrans GL-4 75w, and 75w-80, 75w-85.
If not that ELF TransELF GL-4 series available in the above weights as well?

You ARE in France, right?

 

[Popsy]

Yes, the Gearbox of the Smart if specd for 75W90 GL-4 only

And so is the Colt, which is sharing the same gearbox.

However, the gearboxes of the Fiats are specd for GL4 and/or GL5, or sometimes just GL5. Since it was (at least for me) a bit fuzzy for the Fiats, and I got a decent deal on the Mobil oil, it was a "one size fit them all"

Barchetta got some Motul gear 300.

I have two or three litres of this Mobil oil in my stash, do you really think I should get something else (Castrol syntrans)? Is it because you suspect something wrong with this particular batch of oil, or because it has GL-5 specs too?
The operation of the gearbox wasn't a problem at all, I drained the oil because of a selector "externally" seized (a common problem, the Colt had it too, and it still has the oil the dealer put 35K Km ago)


Also I tried to heat (got lazy and microwaved it...) the oil I drained, when hot it forms less bubbles.

Edit : I am in France, yes, unfortunately^^

 

[zeng]

The Mobil 1 SHC 75W90 has GL5 approval, though not GL4 and MB 235.xx approvals.

However Mobil do recommend this product for applications where GL4 is required.

I see 2 disadvantages here,

a )this fluid has no approvals for GL4 and MB235.xx , and

b )it may encounter 'shiftability' issues due to (a) above.

Having said that, I see this product as having 2 'advantages' which approved Castrol Syntrans doesn't , namely :

c )higher KV@40*C viscosity of 102 cSt (against Syntrans' 76 cSt at 40*C ), thus providing you higher operating viscosity and higher level of components wear protections , and 'possibly' lower operating temperature ; and

d )being GL5 approved , it has higher quantity and percentage of EP additives which would be helpful in hypoid and/or spiral bevel gears boundary lubrication found in differentials/transaxles applications.

From your description, the 'potentials' of shiftability isn't an issue , so you are good to go.

You'll need to bear in mind though ,Lubener's comment on water being contaminating gear oils on oil foaming.

Note: Your effort on 'one size fits all' makes good sense to me.

 

[Popsy]

You are totally right ; once again I got fooled by marketing. It seems this oil doesn't have much approvals, but many recommendations! I got it online and the seller doesn't make difference between approval and recommendation...

Water contamination could be the problem, through the selector maybe ? It seems well protected, but who knows.
I think I'll stick with this oil for now and check regularly, will post a picture next time ! Thank you for answers

 

[Greasymechtech]

Were is Frogland and what other fluids are available at stores/dealerships...?

http://www.mobil.com/UK-English/Lubes/PDS/GLXXENCVLMOMobilube_1_SHC_75W-90.aspx

It looks like a pretty good GL5 that I would use if I couldn't find a GL4. But, I would always make an effort to hunt down a GL4 MT fluid.

Bubbles foam??? Moisture! Post a picture.

Don't reuse fluid.

 

[riggaz]

Don't panic about the bubbles Popsy the Mobil is a very good oil.

We've used the Mobil SHC in our workshop but get better synchromesh performance with Motul Gear 300 75w-90

https://www.motul.com/gb/en/products/recommendation

find your car on the above link and use the recommended product, Motul are French so you should be able to get it reasonably cheap (considering how often you need to change the gearbox oil)

 

[MolaKule]

Originally Posted By: zeng
...d )being GL5 approved , it has higher quantity and percentage of EP additives which would be helpful in hypoid and/or spiral bevel gears boundary lubrication found in differentials/transaxles applications.


There is no such thing as a GL-5 approval. It is a protection rating. The FZG test is the current test used to qualify a lubricant to determine where it would fit in the series of GL-X protection ratings.

The OP never said this was a transmission or a transaxle. If it is a transaxle, it most likley has a spiral bevel gear with a spider gear differential, which have less gear teeth loading and bearing loading than would an offset hypoid. Sooo, it does not need a GL-5 non-dedicated lube but it does need a dedicated (specialized) MTF with the proper additive package.

 

[Popsy]

Yup, it's a basic 5 speed manual gearbox. Oil is shared with differential, as often.

Originally Posted By: riggaz
find your car on the above link and use the recommended product, Motul are French so you should be able to get it reasonably cheap (considering how often you need to change the gearbox oil)

Recommended oil is the Gear 300 75W90, which is usually ~15€/L vs 9€/L for the Mobil.
I got some for the Barchetta and thought the Mobil was good enough for others.

Originally Posted By: Greasymechtech
Were is Frogland and what other fluids are available at stores/dealerships...?
Bubbles foam??? Moisture! Post a picture.


Frogland is where you eat frogs (just kidding, the only way to eat frogs here is to go to a Chinese restaurant), or, more simply, France

I can get many Motul products, Castrol, Elf/Total, Fuchs/Labo, and some exotic oils like Igol/Yacco.
These one catch my attention:

http://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/1A3697364D166E73802578330059B9B3/$File/BPXE-8E2UVT_0.pdf

http://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/C4C6D447E63CAA9580257E3D00453CB7/$File/BPXE-8LT2QJ_0.pdf

Else I'll get Motul gear 300, but it is expensive (and available online only if you want correct price).


But I don't think the oil is really the problem after all. Some of you talked about water contamination, and that is a problem. I don't know where the water can ingress. If there is water ingress, wouldn't the gearbox leak, at least a little? Condensation?
There is absolutely no visible leak on the Smart, nor motor oil neither other fluids

 

[zeng]

Originally Posted By: MolaKule
Originally Posted By: zeng
...d )being GL5 approved , it has higher quantity and percentage of EP additives which would be helpful in hypoid and/or spiral bevel gears boundary lubrication found in differentials/transaxles applications.
There is no such thing as a GL-5 approval. It is a protection rating. The FZG test is the current test used to qualify a lubricant to determine where it would fit in the series of GL-X protection ratings.


I stand corrected.

 

[riggaz]

Originally Posted By: zeng
Originally Posted By: MolaKule
Originally Posted By: zeng
...d )being GL5 approved , it has higher quantity and percentage of EP additives which would be helpful in hypoid and/or spiral bevel gears boundary lubrication found in differentials/transaxles applications.
There is no such thing as a GL-5 approval. It is a protection rating. The FZG test is the current test used to qualify a lubricant to determine where it would fit in the series of GL-X protection ratings.


I stand corrected.

said the man in the orthopedic shoes