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90 gear oil versus EP80/90


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Hi guys.

 

Does anyone have any thoughts in regard to using a straight 90 gear oil in place of an 80/90 EP oil.

 

I know the reverse question has been discussed in regard to using EP oil in older vehicles where bronze components are used but how about using a straight gear oil in place of a hypoid oil?

 

I'm asking as I have purchased a 205 drum of straight gear oil and don't really want to purchase a 205 drum of 80/90 GL4 oil.

 

I'm thinking of using the gear oil in military applications where it states using OEP220.

 

Bear in mind, I'm not covering thousands of miles in our vehicles so I don't see the necessity of using a hypoid gear oil?

 

Any thoughts chaps?

 

Thanks

 

Markheliops

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Hi guys.

 

Does anyone have any thoughts in regard to using a straight 90 gear oil in place of an 80/90 EP oil.

 

I know the reverse question has been discussed in regard to using EP oil in older vehicles where bronze components are used but how about using a straight gear oil in place of a hypoid oil?

 

I'm asking as I have purchased a 205 drum of straight gear oil and don't really want to purchase a 205 drum of 80/90 GL4 oil.

 

I'm thinking of using the gear oil in military applications where it states using OEP220.

 

Bear in mind, I'm not covering thousands of miles in our vehicles so I don't see the necessity of using a hypoid gear oil?

 

Any thoughts chaps?

 

Thanks

 

Markheliops

 

Just a ponderance, but you could add some ZDDP additive to make it EP like. Not sure how well that would work, but it's a consideration.

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Just a ponderance, but you could add some ZDDP additive to make it EP like. Not sure how well that would work, but it's a consideration.

 

Thanks Lauren.

 

From my understanding, EP oil is designed to "stick" better than a straight oil, hence giving longer protection to components.

 

Also EP is Extream Pressure and can withstand the hostile environments of modern hypoid gearing.

 

However, most of our military vehicles don't do excessive mileage at prolonged high speed so I'd like to think, a straight 90 gear oil would be perfectly sufficient?

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I don't get it , a modern automotive straight gear oil is a EP (extreme pressure) oil , a hypoid oil is a extreme pressure oil , but with extra anti-friction & other higher load additives than a std. EP ,,

Both can be mono or multigrade

 

Both could be GL4 or GL5 , GL5 could be iffy with yellow metals unless the manufacturers issue a statement stating otherwise ,,

Edited by ruxy
amd.
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In the early days the EP additive would be lead , then copper , then other stuff.

 

Actually , I did mention the words 'multi-grade' gear oils , technically this is wrong - a true gear oil can't be a multigrade , they don't have polymer chains like engine oils. It is just the range around a median I suppose is the simple description ,,

 

Pick the right modern gear oil and it will be far superior to any SAE type spec. that would be around during WW2 , you could get the original stuff - BUT why wear your gears etc. ?

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I'm thinking pre-OMD220 - surely a straight gear oil would have been used.

 

For example - what gear oil was used in the likes of the Mk1 Stalwart or the early Scammells.

 

Hi Mark,

Going back to my 1963 Military oils book and talking from experience, the army only had one Straight grade (non-EP) gear oil, this was OC600, which was SAE140. This was to be used on any worm drive axle or any axle or gearbox containing bronze type metals. Where a thinner oil was needed in gearboxes, but not an EP, the army specified a SAE50 engine oil OMD330, such as in Bedfords, etc. Other than that it was OEP220 normally.

 

In your quote, I think you mean OEP220.

 

Richard

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I don't get it? A straight 90W GL4 gear oil is an EP90, which is equivalent to an OEP220 and is perfect for your requirement (OEP literally standing for Oil, Extreme Pressure). EP doesn't indicate multi-grade, it indicates that it has additives to deal with extreme pressures (shearing) inside a gear housing.

 

OEP220 can be substituted with an 80w90, as long as it's suitable for use with white and yellow metals and the manufacturer can confirm that.

 

Cheers,

Terry

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I don't get it? A straight 90W GL4 gear oil is an EP90, which is equivalent to an OEP220 and is perfect for your requirement (OEP literally standing for Oil, Extreme Pressure). EP doesn't indicate multi-grade, it indicates that it has additives to deal with extreme pressures (shearing) inside a gear housing.

 

OEP220 can be substituted with an 80w90, as long as it's suitable for use with white and yellow metals and the manufacturer can confirm that.

 

Cheers,

Terry

 

That is my thinking Terry.

 

I intend using it in vehicles that do less that than say 50-100 miles a year.

 

I don't think using a straight 90 gear oil is going to hurt.

 

After all, lots has been written about not using an EP oil in vintage vehicles with bronze components but use a straight gear oil instead.

 

If I was doing motorway or fast A road mileage, I'd certainly put an 80/90 GL4 in.

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What I was saying was that ZDDP is not in gear oil as I understand it.

 

Wikipedia's not always the most accurate, but a google around seems to confirm it - ZDP / ZDDP replaced the lead part of EP oils quite early on. https://en.m.wikipedia.org/wiki/Extreme_pressure_additive

 

More here - https://en.m.wikipedia.org/wiki/Zinc_dithiophosphate

 

If you pick up some of the engine oil additive, which should be the same stuff, it might help.

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The only performance additive that I would add to a straight SAE gear oil would be MoS2 , after that I would advise consult the formulators / study their Tech. Spec. Sheet(s) - why tread on their remit ?

Edited by ruxy
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