Someone please explain VG and weight

[TurboFiat124]

This relates to my post about the HLP 68 hydraulic fluid I've been looking for in the United States for my Trabant's gearbox.

OK, So as of right now I'm trying to determine is Mobil's SHC 626 ISO VG 68 is the same thing as HLP 68. Seems to me the American designation of this fluid goes by ISO (irronic) and in Europe it goes by HLP.

The owner's manual says I can substitute SAE 30 engine oil or SAE 80 gear oil in it's place. But these oils seem to thick.

I poured some of this Mobil SHC 626, ISO VG 68 oil into a container and it is very thin! Actually exactly what I am looking for if it's the same thing as HLP 68 because what I am using right now (10W30 motor oil) seems too thick which won't allow the freewheel device to engage properly.

This makes no sense, wouldn't SAE 30 weight engine oil be much thinner than "68" or do these numbers mean nothing in relationship of one another?

Also HLP 68 is supposed to be a hydraulic fluid? What exactly is the difference between a hydraulic fluid and a gear oil for that matter?

I guess what I am trying to ask is, does the "30" in SAE 30 mean anything compared to viscoity grade? Why would a fluid with a VG of 68 be thinner than SAE 30 motor oil?

Also why does the oil chart below say I could use either SAE 30 engine oil or SAE 80 gear oil? Wouldn't SAE 80 be thicker than SAE 30?

I'm assuming when you start comparing engine oil to gear oil to hydraulic fluid, the numbers don't mean anything?

http://s222.photobucket.com/user/turbofi...643254396775637

 

[Shannow]

From one of the articles up the front of BITOG

Your ISO68 is like an SAE20.

I'm still sticking to my DexIII (not VI)

 

[TurboFiat124]

Then how come this Mobil SHC 626 ISO VG 68 I found is as thin as diesel fuel? That doesn't make any sense?

 

[Shannow]

Your ISO68 should be thinner than the 30, as thin as diesel makes no sense...It should be marginally thicker than ATF

I'm guessing that with your 10W30, you've got an ILSAC GF4/GF5, which will have friction modifiers which may be causing slippage...if the sprags are worn, maybe more so.

 

[TurboFiat124]

Well that might have been an exaggeration. I put some of this SHC 626 in a poly bottle and can shake it up and it moves around and runs down the sides of the bottle like it's as thin diesel fuel.

One thing is weird. When I mix up a batch of 2 cycle fuel, I use one of those similiar poly measuring bottles. I use Lucas 2 cycle oil which is 20 weight. So both should be about the same viscosity based on the chart you posted.

Just from memory the 2 cycle oil clings to the side of the bottle (and funnel) alot longer than this SHC 626 and seems thicker.

I'll will give this stuff a shot and see what happens. Otherwise I'll need to swap transmissions and tear into the one in the car now to see what's worn.

Just seems weird the freewheel device has no issues engaging when I used diesel fuel the other day as a flushing agent but seems to prefer 10W30 over SAE 30. That's why I considered trying 0W30 thinking it might work even better. Especially in cold weather.

Actually cold weather does not seem to be a major factor. The first time this occured it was in August and the next time it occured was a year later in the fall.

The "fix" was dropping down to a thinner lubricant like Dexron III.

 

[weasley]

The '68' (roughly) represents the kinematic viscosity at 40°C (104°F). The equivalence with engine oil most likely matches their KVs at 100°C. For SHC 626 this is around 11.6 cSt. However, SHC 626 has a high VI (around 165) which means that it will not thicken as much as it cools compared to a 10w30 motor oil. The SAE/ISO VG numbers are essentially meaningless at room temperature unless you have more information (ie VI).

 

[supercity]

Lubricating bearings is not that hard and most oil types will do a pretty good job. Hydraulic oil works fine, is usually cheap and easy to get which I guess is the reason it is specified. SHC 626 is a high performance synthetic gear oil with excellent cold temperature properties. If you have access to it I would use it

 

[lim]

In this case ISO and SAE are simply means of expressing viscosity.
VG stands for Viscosity Grade, in your case ISO 68.
Specifications for hydraulic fluids can be a minefield as machinery manufacturers tend to invent and promulgate their own. A common base, which defines your HLP ("hydraulic fluid made from mineral oils with agents to increase corrosion protection, enhance resistance to aging and reduce scoring in areas of mixed friction") requirement is DIN 51524, part 2. The only solution that I can readily come across is Mobil Hydraulic Oil M 46, but there are bound to be others.

Regards, lim

 

[brandini]

Originally Posted By: TurboFiat124
Well that might have been an exaggeration. I put some of this SHC 626 in a poly bottle and can shake it up and it moves around and runs down the sides of the bottle like it's as thin diesel fuel.

One thing is weird. When I mix up a batch of 2 cycle fuel, I use one of those similiar poly measuring bottles. I use Lucas 2 cycle oil which is 20 weight. So both should be about the same viscosity based on the chart you posted.

Just from memory the 2 cycle oil clings to the side of the bottle (and funnel) alot longer than this SHC 626 and seems thicker.

I'll will give this stuff a shot and see what happens. Otherwise I'll need to swap transmissions and tear into the one in the car now to see what's worn.

Just seems weird the freewheel device has no issues engaging when I used diesel fuel the other day as a flushing agent but seems to prefer 10W30 over SAE 30. That's why I considered trying 0W30 thinking it might work even better. Especially in cold weather.

Actually cold weather does not seem to be a major factor. The first time this occured it was in August and the next time it occured was a year later in the fall.

The "fix" was dropping down to a thinner lubricant like Dexron III.


That is a cling test not a viscosity test.

 

[Rand]

how about using a Redline gl-4 gear oil. Its available and good quality.

 

[RF Overlord]

off topic

How did you manage to register a Trabant in the US and where do you get parts?

 

[Ken2]

Let's take your spec apart:
Mobil SHC is a line of synthetic machine oils for "gears, compressors, or bearings." SHC 626 is their label for the ISO 68 stuff.
http://www.mobil1.lt/galery/_mobil1/Pramones/cilindrines/mobil_shc_angl.pdf
http://shop.mobil1.lt/en/produktai/pramonines-alyvos-ir-tepalai/turbinu-ir-cirkuliacines-alyvos/

ISO 68 is the International Standards Organization kinematic viscosity grade measured at 40°C. There are several different viscosity standards used around the world, but ISO is used for just about everything these days except vehicles.

As the chart shows, ISO68 is very close to 20 wt engine oil (different viscosity measuring scale) and 80 wt gear oil (different designation of the same scale as engine oil--the number 80 tells us that it is gear oil, not engine oil).

So, look for an ISO 68 machine oil in a 5 gallon can at an industrial lubricant supplier, synthetic if you can find it. Or use a straight 20 wt engine oil. Or use a straight 80 or 80W weight gear oil. The synthetic ISO 68 machine oil will probably work best regardless of brand.

 

[Yah-Tah-Hey]

The Mobil SHC 600 series is for industrial application. We used it in coal conveying equipment because of very cold winters in northwest Colorado. Never saw the product for use in motor vehicles. I think SHC is the base stock for most of Mobil's synthetic products.

 

[Jetronic]

Originally Posted By: TurboFiat124
This relates to my post about the HLP 68 hydraulic fluid I've been looking for in the United States for my Trabant's gearbox.

OK, So as of right now I'm trying to determine is Mobil's SHC 626 ISO VG 68 is the same thing as HLP 68. Seems to me the American designation of this fluid goes by ISO (irronic) and in Europe it goes by HLP.

The owner's manual says I can substitute SAE 30 engine oil or SAE 80 gear oil in it's place. But these oils seem to thick.

I poured some of this Mobil SHC 626, ISO VG 68 oil into a container and it is very thin! Actually exactly what I am looking for if it's the same thing as HLP 68 because what I am using right now (10W30 motor oil) seems too thick which won't allow the freewheel device to engage properly.

This makes no sense, wouldn't SAE 30 weight engine oil be much thinner than "68" or do these numbers mean nothing in relationship of one another?

Also HLP 68 is supposed to be a hydraulic fluid? What exactly is the difference between a hydraulic fluid and a gear oil for that matter?

I guess what I am trying to ask is, does the "30" in SAE 30 mean anything compared to viscoity grade? Why would a fluid with a VG of 68 be thinner than SAE 30 motor oil?

Also why does the oil chart below say I could use either SAE 30 engine oil or SAE 80 gear oil? Wouldn't SAE 80 be thicker than SAE 30?

I'm assuming when you start comparing engine oil to gear oil to hydraulic fluid, the numbers don't mean anything?

http://s222.photobucket.com/user/turbofi...643254396775637


Hydraulic fluid doesn't contain antiwear additives or friction reducing agents. In fact, some hydraulic fluid contains stuff like you would find in limited slip gear oils or ATF fluid; increased friction when the fluid film is broken.

gear oil SAE 80 and engine oil SAE30 are likely the thinnest oils commonly available in the warschau pact countries.

all the viscosity grades on the same horizontal line are the same viscosity, but you must read the correct temperatures: hydraulic oils are rated at 40°C, engine/gearbox oils at 100°C!