15w-40 engine oil for hydrulics

I'm going to change my hydraulic oil from hydraulic 46 that's in it now, to 15w-40 engine oil.

But am not sure if it should be engine oil meant for diesel or petrol? or if it matters at all.
my understanding is that there is different additives in different types and brands.

Does anyone know if it matters or have a recommendation?

It's for my PC30mr-1, Komatsu can't tell me.

My question would be why? That machine only holds 50 liters hydraulic....

lantraxco said:

My question would be why? That machine only holds 50 liters hydraulic....

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I don't know if you would remember but I posted a thread called not another pc30mr-1 problem, a while back, and I explained about having problems with some hydraulic functions not working on occasion in hot weather when the oil got thin.
All this started way back after changing the oil, and after recently getting a service manual it says doesn't list 46 but does says 15w40 as an option.
So my theory is the much higher viscosity should solve the problem, and it didn't have the problem before I changed the oil over.

With summer coming up I don't want to be jiggling the controls every 20mins trying to get the bucket off the ground. So though I would try this, its alot cheaper than having komatsu come look at it.

Ah, well if Kommie says it's acceptable, go for it. 15W40 should be diesel oil, over here at least you would find petrol engines take a 10w30 or 10w40, diesels take the 15w40. I use Chevron Delo 400, Shell Rotella is also popular. Valvoline and Castrol are also available here, any of those should be good. What do you have locally?

I've seen some Valvoline 'diesel' 15w40 here cheap so might go with that, i assumed diesel would be the 'type' but here there are lots of 15w40 types, some say just for diesel or just for petrol with different additives, but maybe it would't matter, can't find all that much info regarding engine oil in hydraulics.

If you're in a hot climate in your part of Oz you could also consider going to AW68 hydraulic oil. In hot climates that worked for us on a lot of hydraulic systems that were specced with ISO46 oil.

Nige said:

If you're in a hot climate in your part of Oz you could also consider going to AW68 hydraulic oil. In hot climates that worked for us on a lot of hydraulic systems that were specced with ISO46 oil.

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Yeah i was originally going to swap it to 68 but looking at some viscosity charts the the 15w40 looks even better in extreme heat, the weather does get hot hear, in summer days over 40c isn't uncommon, around 35c often.
Prob wouldn't hurt to have another oil cooler or fan but will prob sell this old machine after another 1000hrs or less.

I've got mixed thoughts putting 15w40 in my machine but its in the service manual so i think i'll go with it.

I use a multi grade hydraulic oil in everything. Saves on inventory and it's good year 'round here. ISO AW 32/46/68.

I didn't even know they had multi grade hydraulic oil, just looked them up then, they sound like a good idea.

I ended up changing it to 15w40, it seems to be working well, and i'm not 100% sure but i think my pump is quieter now.
As for it solving the problem of the sticking valves, i will only know in a month or two when the weather gets hot, but I've got a good feeling about it.