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#4481524 - 08/07/17 07:29 AM Compatibility mixing SAE 10W30 and AW46 in backhoe
PeteC Offline


Registered: 08/07/17
Posts: 5
Loc: TX
Would there be any compatibility issues if ~4 gal of AW46 hydraulic oil was inadvertently added to top up a Komatsu backhoe hydraulic system (approx. 50 gal) that is likely filled with SAE 10W30 per spec? The specs in the manual also indicate a 46 grade biodegradable hydraulic oil is acceptable so on a viscosity basis it would seem to be ok. The manual does indicate that 10W30 and biodegradable oils are not compatible, but the AW46 in this case is regular non-bio oil. The machine hasn't been run, so I'm trying to determine if I need to drain and waste 50 gal of oil or if this is not a big deal. Some info I have read indicates the two oils are laregely the same with the difference being the additives in the hydraulic oil.

Thanks!

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#4481603 - 08/07/17 09:24 AM Re: Compatibility mixing SAE 10W30 and AW46 in backhoe [Re: PeteC]
zeng Offline


Registered: 09/01/15
Posts: 2199
Loc: Malaysia
[email protected]*C of 10W30 is 70-90ish cSt; and AW46 is 46 cSt.
So, you're marginally thinning the sump.
Engine oil additives is more than adequate for a hydraulic application , other than emulsibility/demulsibility.
Taking a step back, you should be ok ...... as long as sump temperature is say, below 80*C.

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#4481655 - 08/07/17 10:13 AM Re: Compatibility mixing SAE 10W30 and AW46 in backhoe [Re: zeng]
PeteC Offline


Registered: 08/07/17
Posts: 5
Loc: TX
80C = 176F I believe and I wouldn't be surprised to see hydraulic oil temps exceed that in 104F+ weather under extended work. Of course I don't think I'll be doing any extended work in 104F+ weather myself in an open cab anyway so that might not be an issue.

The Komatsu manual talks about incompatibility between the 10W30 and biodegradeable 46 crating insoluables that will clog the filter, but I'd hope that wouldn't be the case with ordinary non-bio AW46.

I think the AW46 will be around 8-9% of the total in the system so I don't think it will affect viscosity too much.

Thanks

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#4483897 - 08/09/17 04:43 PM Re: Compatibility mixing SAE 10W30 and AW46 in backhoe [Re: PeteC]
DWC28 Offline


Registered: 07/31/03
Posts: 207
Loc: Houston, TX
Bio oils are usually zinc free and engine oils and hydraulic oils contain zinc. Combining zinc and non-zinc oils has clogged many a filter. Engine oils with detergents emulsify water, hydraulic oils may but probably don't. For a backhoe that should not matter. Caterpillar ran engine oils in the hydraulics for years.

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#4519366 - 09/18/17 11:54 AM Re: Compatibility mixing SAE 10W30 and AW46 in backhoe [Re: PeteC]
MolaKule Offline


Registered: 06/05/02
Posts: 19135
Loc: Iowegia - USA
Originally Posted By: PeteC
...The specs in the manual also indicate a 46 grade biodegradable hydraulic oil is acceptable so on a viscosity basis it would seem to be ok. The manual does indicate that 10W30 and biodegradable oils are not compatible, but the AW46 in this case is regular non-bio oil...

Thanks!


???

Are they saying that any ISO 46 Biodegradeable Hydraulic Oil is NOT compatible with ANY 10W30 engine oil ... or are they saying that Biodegradeable Engine Oil is incompatible with any other engine oil?

It is not clear what exactly is being stated in terms of their compatibility objections.


Edited by MolaKule (09/18/17 11:57 AM)

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