Destroying the OMD115 myths.

[isuzurover]

For some strange reason some people think that the oils used by the military are the best oil to use in a 4BD1(T). This is despite the fact that most army 4BD1(T)s did very few km compared to 4BD1(T)s in trucks.

However, that is neither here nor there. The myth we are destroying here is that a 20W60 diesel oil is equivalent to OMD115. The consensus seems to be that OMD115 is an SAE40 oil.

The attached graph shows the minimum and maximum viscosity for the SAE40 spec, together with a 15W40, 20W60 and Monograde 40 (Detroit diesel engine) oil.

EDIT: Updated graph to show SAE30 and SAE40 ranges, see document on next page showing that OMD115 is (or was) SAE30.

http://www.aulro.com/afvb/attachments/coil-sprung-military-land-rovers/116245d1478432718-destroying-omd115-myths-oil_vis3.jpg

http://www.aulro.com/afvb/attachments/coil-sprung-military-land-rovers/116245d1478432718-destroying-omd115-myths-oil_vis3.jpg

https://www.aulro.com/afvb/

http://www.aulro.com/afvb/attachments/coil-sprung-military-land-rovers/116294d1478507287-destroying-omd115-myths-oil_vis4.jpg

[isuzurover]

I also suspect that OMD115 was selected for commonality as it is required by the detroit diesels in the ASLAVs.

[workingonit]

Thanks Isuzu. Unfortunately I'm not familiar with the issue. Which oil are you supporting (assuming the 20W60)?

In this example the SAE40 is not actually from a can labelled OMD115 hence the '?' ? :)

[workingonit]

If you had asked me off the top of my head I would have said use the 15w40. From memory I tried a Penrite 20w40 in my troop carrier and it took some minutes for the oil pressure guage to drop to what I considered normal - I assume OK for the bearings but not sure what extra stress it puts on the pumping components - probably nothing to worry about!? Odd that 15w40 never gave the same initial high pressure guage reading as 20w40, given both start at 40.

[isuzurover]

Thanks Isuzu. Unfortunately I'm not familiar with the issue. Which oil are you supporting (assuming the 20W60)?

In this example the SAE40 is not actually from a can labelled OMD115 hence the '?' ? :)

There are a group of people on here who use 20W60 and 20W50 oils and argue that they are equivalent to OMD115.

I am showing here that this is not correct. As you say, a 15W40 oil is the closest to OMD115 spec.

There are also some on here/remlr who use monograde SAE40 oils as they believe that matches the OMD115 spec. IMHO that is just silly. If you live in FNQ or Darwin you may get away with a monograde oil, but everywhere else you are just asking for accelerated wear on startup. Plus monograde oils are really a dead end as far as R&D goes, multigrade oils have much better additive packages.

[Not_An_Abba_Fan]

If you had asked me off the top of my head I would have said use the 15w40. From memory I tried a Penrite 20w40 in my troop carrier and it took some minutes for the oil pressure guage to drop to what I considered normal - I assume OK for the bearings but not sure what extra stress it puts on the pumping components - probably nothing to worry about!? Odd that 15w40 never gave the same initial high pressure guage reading as 20w40, given both start at 40.

Other way around actually, the first number is the cold viscosity. The 20W40 will be a bit thicker cold than the 15W40.

[isuzurover]

Other way around actually, the first number is the cold viscosity. The 20W40 will be a bit thicker cold than the 15W40.

Yes that is correct. You can see from the graph above that the monograde oils have a steeper slope so are more viscous at low temperatures. Below 10 degrees they really start to deviate from the fitted line, and become even more viscous (even worse than the 20W).

[workingonit]

Thanks N.A.A.F. I originally thought as you described. A 'thin' (low viscosity) for cold starts, getting 'thicker' (higher in viscosity) to provide better protection to the bearings as the engine warmed up.

But when I looked at the graph I thought I must be wrong, as it seems the colder the engine the higher the viscosity and vice versa. Looking at wiki further confuses me quote for mongrade "A specific oil will have high viscosity when cold and a lower viscosity at the engine's operating temperature" but with additives "cause the multi-grade oil to have the viscosity of the base grade when cold and the viscosity of the second grade when hot"

I'm thinking rightly or wrongly that the graph presented is fine for monogrades ie dense when cold, but thin when hot. Wouldn't you expect a different line (more horizontal or curved) for multigrades than presented here given the viscosity is 'dynamic'?

[87County]

It has been reasonably well established that a 15W-40 diesel engine oil can be used in the engine, gearbox and tc of any military or civilian Isuzu engined 110. Castrol RX Super seems to be most frequently recommended but any oil with an equivalent rating can be used.

Quite straightforward really.

[isuzurover]

Thanks N.A.A.F. I originally thought as you described. A 'thin' (low viscosity) for cold starts, getting 'thicker' (higher in viscosity) to provide better protection to the bearings as the engine warmed up.

But when I looked at the graph I thought I must be wrong, as it seems the colder the engine the higher the viscosity and vice versa. Looking at wiki further confuses me quote for mongrade "A specific oil will have high viscosity when cold and a lower viscosity at the engine's operating temperature" but with additives "cause the multi-grade oil to have the viscosity of the base grade when cold and the viscosity of the second grade when hot"

I'm thinking rightly or wrongly that the graph presented is fine for monogrades ie dense when cold, but thin when hot. Wouldn't you expect a different line (more horizontal or curved) for multigrades than presented here given the viscosity is 'dynamic'?

All oils are thick (more viscous) when cold and thin (less viscous) when hot. However multigrade oils are blended to reduce the rate of viscosity increase as temperature decreases. That is why you see the 15W40 line crossing over the 3 monograde 40 lines. The difference looks small, however the y-axis is a log scale. Plus the difference gets more pronounced below 10oC.

[ozeraser]

Well I cant talk to this OMD115 stuff as im not knowledgable in it. But Isuzu themselves didnt recomend the use of synthetics in the 4BD1 engine in a NPR 400 when i asked. Penrite recomend that oil for the 4bd1 in all NPR trucks. So personally thats what I use. Its a bit thicker but shes an old engine.

[isuzurover]

It has been reasonably well established that a 15W-40 diesel engine oil can be used in the engine, gearbox and tc of any military or civilian Isuzu engined 110. Castrol RX Super seems to be most frequently recommended but any oil with an equivalent rating can be used.

Quite straightforward really.

You would think so, but this and the Remlr forums are filled with statements like:


(Penrite HPR Diesel 20W60) Satisfies OMD115.
OMD115 is what the Army documentation say should be used in a Perentie.


I have decided to go with Castrol deisel straight 40


...I use Penrite HPR40 25W-70.
...
The Perentie manual as published by the ADF says to use SAE40 oil.
Penrite HPR40 oil is SAE40.
I spoke to a Penrite rep, showed him the documentation and asked for his recommendation. He pointed to HPR40 oil.

[DazzaTD5]

As the OP (isuzurover) has rightly shown with some info, a 20W60 really isnt the oil to be using in a small light vehicle (light truck) engine. and he also rightly points out it was prolly done for commonality.

A MIL spec isnt the bee all and end all to everything, its certainly not a substitute for an AS, ISO, SAE or a manufacturers spec.

While I dont know the full in and outs of getting a MIL spec on a part or chemical, no doubt its part of their internal procedures, partly to ensure basic requirements are met such as having MSDS, tech data, etc etc for a given part or chemical. Just like with other large organisations such as mining companies, most you just cant rock up on side with all sorts of chemicals in the back of your vehicle, they need to be approved for site use etc etc.

And compared to private companies often Gov bodies such as the Military are slow to respond or change procedures, or specs so an oil may well have a MIL spec but may well be outdated for use now (or 30 years ago).

A good multi fleet semi synthetic 10W40 or 15W40 diesel engine oil would be more than perfect for the Isuzu engine.

The only time I use a 20W60 or a 40W70 is to keep running a flogged out old oil burning engine that ive changed out one or two spun big end bearings. We always have a chuckle (as would any professional) when a engine needs such thick oil.

Regards
Daz

[DazzaTD5]

I certainly cant understand anyone using a straight SAE weight engine oil over a multi grade engine oil for any general purpose engine in any light vehicle,

IMHO that really is a complete lack of understanding on engine oil, how an engine functions, and how multi grade engine oils work.

We arent living in the 50's, oil and the wheel have advanced well beyond the stone age.

Regards
Daz

P.S wooo now I see someone is using a 25W70 ????? thats nuts.
*If a engine oil is a 25W70 which is a multi grade oil, then it cant be a SAE40 single/mono grade oil. and vise versa.
*Ask Justin C what he runs in his Isuzu 110, I bet beer its not a 20W60 or any mono grade engine oil.

[isuzurover]

...Penrite recomend that oil for the 4bd1 in all NPR trucks. So personally thats what I use. Its a bit thicker but shes an old engine.

Penrite are the only company that do (AFAIK). That may be because they don't have a thinner oil to offer with a sufficient rating.
Many Penrite oils seem to be thicker than ideal.

[isuzurover]

I certainly cant understand anyone using a straight SAE weight engine oil over a multi grade engine oil for any general purpose engine in any light vehicle,

IMHO that really is a complete lack of understanding on engine oil, how an engine functions, and how multi grade engine oils work.

We arent living in the 50's, oil and the wheel have advanced well beyond the stone age.

Regards
Daz

P.S wooo now I see someone is using a 25W70 ????? thats nuts.
*If a engine oil is a 25W70 which is a multi grade oil, then it cant be a SAE40 single/mono grade oil. and vise versa.
...

Agree 100%

As I said in the 2nd post, **if** OMD115 is really a straight SAE40 as all the mil guys suggest, it is about as far from the best choice for a 4BD1 as you can get, and likely only used because the 2-stroke diesels in the ASLAV which spec SAE40.

[Aussie Jeepster]

This quote from a Leopard tank document tends to indicate/support that OMD115 is a single weight SAE30 oil.

"Extension of oil change intervals to two years for the Leopard Main Battle Tank (MBT) is under consideration by NATO countries. At the 15th International Leopard Vehicle Technical Working Group meeting [1], a final report was provided on a European trial which involved the extension of oil change intervals for Leopard vehicles to periods in excess of two years when operating with a multigrade 15W40 oil (Nato 0-236). Results for 800 oil samples from more than 200 vehicles were summarized in this report. No unacceptable deterioration of the oil or abnormal wear in the vehicles was found for oil change intervals extending up to 30 months. In Australia, a single grade SAE-30 oil, OMD-115 (Nato 0-238) is used for crankcase lubrication of AS-1 Leopard Powerpacks rather than the Nato 0-236 oil. Current Army practice is to change the lubricant in the Leopard AS-1 every 6 months or 1000 kIn. This interval was based on recommendations by the engine manufacturer (MTU), that the oil be changed after 5000 litres of fuel had been consumed, which is approximately 1200 km for Australian operation conditions. Extension of the oil change interval would not only reduce expenditure on replacement oil, but also allow greater flexibility in servicing requirements for the vehicles. This study, on the feasibility of extei|ding the oil change intervals in the Leopard AS-1 vehicles when operating with OMD-115 oil under Australian conditions, was carried out at the request of the Australian Army Maintenance Engineering Agency (MEA).

3.2 Oils The crankcase oil was OMD- 115, a monograde SAE30 diesel engine oil qualified to MIL-L-2104D. This is the standard diesel engine crankcase oil used by the Australian Army for almost all diesel powered vehicles. The transmission oil was 0X47, a monograde SAE10 hydraulic transmission fluid to Detroit Diesel Allison specification TES 122."

[isuzurover]

This quote from a Leopard tank document tends to indicate/support that OMD115 is a single weight SAE30 oil.

"Extension of oil change intervals to two years for the Leopard Main Battle Tank (MBT) is under consideration by NATO countries. At the 15th International Leopard Vehicle Technical Working Group meeting [1], a final report was provided on a European trial which involved the extension of oil change intervals for Leopard vehicles to periods in excess of two years when operating with a multigrade 15W40 oil (Nato 0-236). Results for 800 oil samples from more than 200 vehicles were summarized in this report. No unacceptable deterioration of the oil or abnormal wear in the vehicles was found for oil change intervals extending up to 30 months. In Australia, a single grade SAE-30 oil, OMD-115 (Nato 0-238) is used for crankcase lubrication of AS-1 Leopard Powerpacks rather than the Nato 0-236 oil. Current Army practice is to change the lubricant in the Leopard AS-1 every 6 months or 1000 kIn. This interval was based on recommendations by the engine manufacturer (MTU), that the oil be changed after 5000 litres of fuel had been consumed, which is approximately 1200 km for Australian operation conditions. Extension of the oil change interval would not only reduce expenditure on replacement oil, but also allow greater flexibility in servicing requirements for the vehicles. This study, on the feasibility of extei|ding the oil change intervals in the Leopard AS-1 vehicles when operating with OMD-115 oil under Australian conditions, was carried out at the request of the Australian Army Maintenance Engineering Agency (MEA).

3.2 Oils The crankcase oil was OMD- 115, a monograde SAE30 diesel engine oil qualified to MIL-L-2104D. This is the standard diesel engine crankcase oil used by the Australian Army for almost all diesel powered vehicles. The transmission oil was 0X47, a monograde SAE10 hydraulic transmission fluid to Detroit Diesel Allison specification TES 122."

Thanks.
Link to document:
http://www.dtic.mil/dtic/tr/fulltext/u2/a267088.pdf

[isuzurover]

Updated graph to show SAE30 and SAE40 ranges

http://www.aulro.com/afvb/attachments/coil-sprung-military-land-rovers/116294d1478507287-destroying-omd115-myths-oil_vis4.jpg

http://www.aulro.com/afvb/attachments/coil-sprung-military-land-rovers/116294d1478507287-destroying-omd115-myths-oil_vis4.jpg


EDIT: There is also this document from 2014 which conflicts with the 1993 document - unless the spec for OMD115 was changed from SAE30 to SAE40

http://www.aulro.com/afvb/attachments/coil-sprung-military-land-rovers/113234d1472530313-6x6-using-oil-veh_g203_landrover_110_6x6_all_types_light_repair-lubrication.pdf

For those who like Penrite oils this document lists 2 15W40 diesel oils: https://www.penriteoil.com.au/tech_pdfs_new/Jan2014/Product_Catalogue_Defence.pdf

[Jonnooh]

There are a group of people on here who use 20W60 and 20W50 oils and argue that they are equivalent to OMD115.

I am showing here that this is not correct. As you say, a 15W40 oil is the closest to OMD115 spec.

There are also some on here/remlr who use monograde SAE40 oils as they believe that matches the OMD115 spec. IMHO that is just silly. If you live in FNQ or Darwin you may get away with a monograde oil, but everywhere else you are just asking for accelerated wear on startup. Plus monograde oils are really a dead end as far as R&D goes, multigrade oils have much better additive packages.

The Army service instructions state "SAE Grade 40 (OMD-115)" so it bemuses me why some people think it is something else.

[Mick_Marsh]

OMD-115 facts:

Specification: MIL-L-2104E
NATO code: O-238
SAE Grade 30
API CDII
Viscosity: 9.7-12.5mm?/s @ 100?C
Viscosity Index (VI): 75 (min)
Pour Point: -18?C (max)
Flash Point COC: 220?C (min)

NSN 205l : 9150-66-017-3041
NSN 20l : 9150-66-089-6558

https://www.aulro.com/afvb/

So, what does that tell us?

[isuzurover]

OMD-115 facts:

Specification: MIL-L-2104E
NATO code: O-238
SAE Grade 30
API CDII
Viscosity: 9.7-12.5mm?/s @ 100?C
Viscosity Index (VI): 75 (min)
Pour Point: -18?C (max)
Flash Point COC: 220?C (min)

NSN 205l : 9150-66-017-3041
NSN 20l : 9150-66-089-6558

http://www.aulro.com/afvb/attachments/coil-sprung-military-land-rovers/116338d1478609804-destroying-omd115-myths-viscosity-graph.jpg

So, what does that tell us?

So now you are saying OMD115 is SAE30 instead of SAE40?

That plot tells us nothing because whomever plotted it hasn't used a log scale for the y-axis. Have a look at my plots which show the same data.

[Aussie Jeepster]

I really think we are getting into a lather over nothing!
Yes, it might be nice to know the details, but essentially we are talking about a 1990 model truck engine. It does not have ceramic bearings or berrylium lobes, - it's just a diesel truck engine!
Normal diesel engine oil, like Castrol RX will do me.

[isuzurover]

I really think we are getting into a lather over nothing!
Yes, it might be nice to know the details, but essentially we are talking about a 1990 model truck engine. It does not have ceramic bearings or berrylium lobes, - it's just a diesel truck engine!
Normal diesel engine oil, like Castrol RX will do me.

Yes it is all a bit silly. However a lot of people seem to want to match the military oil spec (OMD115). This is despite the fact that every oil supplier recommends a 15W40 oil (e.g. RX Super) for the 4BD1(T). The only exception to this is Penrite which recommend a 20W60 for a 4BD1(T) in a landie but a 15W50 for the same engine in a truck.

Depending on which document you look at, OMD115 is either a straight 30 or a straight 40. Which means that any XXW40 oil will be a match at operating temperatures.

Mick Marsh (who has said he uses 25W70) is trying to claim that this oil meets OMD115 because the viscosity curves match up at low temperatures - which is actually a really bad thing!!!

[87County]

Yes it is all a bit silly.

.....

Mick Marsh (who has said he uses 25W70) is trying to claim that this oil meets OMD115 because the viscosity curves match up at low temperatures - which is actually a really bad thing!!!

hmmm, interesting

[DazzaTD5]

Well IMHO....

I dont think its all a bit silly or even getting carried away, its staying on topic and at the end of the day, people can put whatever they want in their own vehicle.

If we look at the data from isuzurover and Mick_Marsh, comparing the MIL spec OMD-115 (keep in mind thats not a product, its a required specification that has been made by the military and nothing more) we can deduct and see the following:

*A mono or single weight SAE 30 engine oil meets the spec at the SAE standard test at 100 deg C (in fact it exceeds the spec).
*At the lower temperature test of 40 deg C it also does well.
*the multi grade 15W40 actually doesnt do as well which would steer me to the obvious better choice of using a 10W30, or 10W40 or even better a 5W40 engine oil.
*Keep in mind a multi grade engine oil is always going to do better, on cold engine start up, which is the most critical wear issue on an engine, you need that good/instant flow of engine oil to components.
*Sure if you run a fleet of trucks and use a diesel engine oil such as Shell Rimula, then throwing it in your Isuzu powered Land Rover 110 is going to be fine, keep in mind truck engines are subjected too far greater stresses than an engine in a little 2 ton Land Rover.

*The big fat elephant in the room that makes the MIL spec OMD-115 fall on its arse is the requirement of a VI rating of only 75 ????? thats laughable, A VERY BASIC EXPLANATION OF "VI" rating, It is the rate of change of viscosity between two temperatures. The lower the VI rating, the more the drop in viscosity as the oil warms up. The higher the VI rating, the less the drop in viscosity as the oil warms up., so the higher the VI rating the better. The average for modern multi grade engine oil is round 130 - 150, making the requirement of a VI rating of 75 look like something from the 1950's or 1960's.

IMHO, so take this one as you will...
I use on all customers Isuzu powered 110's, Penrite HPR DIESEL 5 5W40 semi synthetic (actually I use it on all 110 & Defenders), it has the good flow properties of a SAE 5 on that oh so critical cold engine start up but performs as a SAE 40 engine oil at the standard 100 deg C temperatures.

Which always makes the odd owner or mechanic say that a 5W40 multi grade engine oil is too thin to use on these old engines, that my friends is simply a myth that cant be supported by factual information.

All the above is some very very basic info and I have left out a LOT and I mean a hell of a LOT of information, this is oil chemical science, the more you get into it, the more your head will spin.

Just a starting point, the more you read and get into it, the more you will find:
https://en.wikipedia.org/wiki/Motor_oil
Motor Oil Viscosity Grades Explained in Layman's Terms (http://www.upmpg.com/tech_articles/motoroil_viscosity/)
Basics of viscosity and the flow behavior of liquids (http://www.viscopedia.com/basics/)
Oil Viscosity Explained (http://www.kewengineering.co.uk/Auto_oils/oil_viscosity_explained.htm)
What Every Motorist Should Know About Motor Oil (http://www.aa1car.com/library/motor_oil_605.htm)

Regards
Daz

[isuzurover]

I think the biggest problem a lot of people have is that they don't understand the differences between SAE winter and summer (hot/cold) ratings. It is a bit counterintuitive that the SAE 0-25(W) is a lower number than the summer number. So many people think a 20W60 the 20 is actually the summer rating.

If we rated them by kinematic viscosity the OMD115 would be a 1600(c)12(h) or similar (i.e. 1600 mm2s-1 during cold starts and 12 at operating temp). I am using c for cold and h for hot here so as not to confuse the W for winter in the SAE rating system.

With a rating system like that people would choose the oil that has the lowest cold viscosity (i.e. a 0W or 5W - which is about a 50(c)12(h) in kinematic viscosity). Because a viscosity of 50 (mm2s-1) or so is much closer to the 12 (mm2s-1) you want to have at operating temperature.

[Trigger82]

Just curious as to why so many are fascinated with what the military used.

Have these same people tried talking to an "Isuzu" dealership to see what Isuzu themselves used in the day?????
Id almost bet a left nut it wasnt what the military used.

If I get a chance tomorrow I'll contact a dealer

[isuzurover]

Just curious as to why so many are fascinated with what the military used.


Good question.




Have these same people tried talking to an "Isuzu" dealership to see what Isuzu themselves used in the day?????
Id almost bet a left nut it wasnt what the military used.

If I get a chance tomorrow I'll contact a dealer

My 1988 Isuzu WS manual specifies 10W30.

[LandyAndy]

Ben's got a bone,aint non of you going to get it off him:p:p:p:p:p:p:p:p:p:p.
Good boy Ben:):):):):):):):):):):):):):):):):)

ENJOY
Andrew