Mixing gearbox oil brands - problem?

[mick]

Originally Posted by Alan Priddy

Might have to disagree with this. To my knowledge there isn't an oil made that will still work when it is contaminated with water. It's the specification of the oil that is important not the brand name. In a clutched unit the destruction is caused by the water contaminated oil generating steam inside which lifts the bonding elements Alan P

Same here I asked at millers oils a while back had a word with there tech guy about the gearbox oil for my 2 and he said there is no difference as long as the grades and iso s are right same as with mixing brands

[Nos4r2]

Originally Posted by Alan Priddy

Might have to disagree with this. To my knowledge there isn't an oil made that will still work when it is contaminated with water. It's the specification of the oil that is important not the brand name. In a clutched unit the destruction is caused by the water contaminated oil generating steam inside which lifts the bonding elements Alan P

Bear in mind the original question is about outboards which don't have clutches as such-an outboard dog clutch is a totally different animal and doesn't have pressure plates.

I've done my own 'tests' on this-using a 1973 Mercury 500 with a totally screwed propshaft seal. The seal was so bad it needed topping up with oil after a week of being out of the water as it dripped. Both times the lower unit was filled with fresh oil before using the engine.

After about 2-3 hours running, using car hypoid EP90 the resultant mess was totally white and when rubbed between bare fingers, it didn't even feel like oil. There was no obvious lubrication taking place.

After approximately 3 hours running and a night in the water using Quicksilver Premium gear oil, the resultant mess (and yes, both looked like mayo) wasn't anywhere near as white (no indicator as the QS oil was darker in the first place), but was still slippery when rubbed between bare fingers and was obviously lubricating to a degree.

Never mind what a sales rep says. I've been around long enough to work out that however knowledgable they sound,It's mostly bull**** designed to cover up that they actually know very little about the products they are selling bar what's been given them in their promo packs.
Anyone with half a brain can con a salesman with a limited tech knowledge into selling a product and thinking it's saving the world. (HHO gas anyone? ) and Miller's tech guy certainly isn't going to do them out of sales by saying that 'marine' brands are superior at a specific application. Admitting you don't sell the best product for the job is a pretty quick way to the dole queue.

[mick]

Don't think there entirely full of bull as I wanted some ATF for a disco3 and there's wasn't up to the ISO and same with the steering fluid for the boat

[uncle al]

when I was a lad and learning my trade it was drumed into me that you dont mix oils hypoid/ep and minerall and synthetic, yes some will mix safely and some wont, as i have never seen or found a list that will show me which will mix and which wont mix ,to be on the safe side i never mixed oils,

[Nos4r2]

Originally Posted by mick

Don't think there entirely full of bull as I wanted some ATF for a disco3 and there's wasn't up to the ISO and same with the steering fluid for the boat

Easy to read a bottle or a pdf

[m chappelow]

If you are going to mix I don't think there would be much of a problem as long as their both marine grade hypoid ,even if mineral or synthetic its not like mixing the actual powerhead engine oils with higher working temperatures .

Main difference about the marine grade hypoid stuff compared to the plain car stuff is that with water contamination it doesn't emulsify up as quickly though left eventually it will still turn to rice pudding & separate
Think the biggest problem with sea water entering the gear box is the corrosion & the abrasiveness aspect of the saltwater if left .

As Dirk diggler says for the amount in an outboard you may as well replace the whole stuff .

[Alan Priddy]

It's all down to the specification of the product not the brand name or the EP rating. Oils can be mixed providing the manufacturing specification is the same. The colour means nothing as each product is only dyed for identification. Alan P

[Nos4r2]

Originally Posted by Alan Priddy

It's all down to the specification of the product not the brand name or the EP rating. Oils can be mixed providing the manufacturing specification is the same. The colour means nothing as each product is only dyed for identification. Alan P

Which is what I said

If anyone decides to make a Quicksilver or Yamalube EXACT equivalent, I'll use it. However, there doesn't appear to be anything on the market that works as well as they do if you get water in the oil-ISO specs or not.