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Re: Factory Maintenance Schedule-Ideas?

Thu Jan 13, 2011 2:05 pm

An experiment comparing energy losses from "thick" vs. "thin" transmission oils

Written by Roger - electric Forsa owner.
http://tech.groups.yahoo.com/group/ev/message/35167
Apr 12, 2007

RE: Sprint/Metro Drivetrain losses

I had written:

> The tranny is full of fresh 75W90 gear oil, per the manual,
> however, I've been advised that the manual is wrong and a GM
> semi-synthetic lube is what should be in there. I'm
> skeptical that the lube alone could be responsible for this
> sort of loss, but since an oil change is easier than
> rebuilding the tranny, I'll try that first ;^>

As it turns out, it seems (from checking a partial bottle remaining in
the garage) that the tranny is actually full of 80W90, not 75W90 as I
originally wrote.

I put the car on stands again (under the frame with the suspension at
full droop since the suspension angle didn't seem to affect energy
consumption in my earlier tests and I feel better with the stands under
the frame when I'm going to be getting under the car).

All following energy consumption observations are based on battery pack
voltage and current as reported by my E-Meter.

I spun the wheels in 2nd for a few minutes to warm things up first, then
measured energy use in each gear at 40kph (except 1st, which was
measured at 30kph):

5th 23.4A @ 123.5V (116.3Wh/mi or 72.2Wh/km)
4th 22.9A @ 123.0V (113.4Wh/mi or 70.4Wh/km)
3rd 25.5A @ 123.0V (126.2Wh/mi or 78.4Wh/km)
2nd 30.8A @ 121.5V (150.6Wh/mi or 93.6Wh/km)
1st 37.5A @ 121.5V (244.5Wh/mi or 151.9Wh/km)

After draining the old fluid, I poured in a half litre or so of Varsol
and spun the wheels for a minute or two to flush things out:

2nd 22.5A @ 123.0V (111.4Wh/mi or 69.2Wh/km)

This was then drained, and the tranny filled with 2.5 litres of the
recommended AC Delco Synchromesh fluid (p/n 89021808, IIRC):

5th 16.1A @ 123.0V (42kph, 75.9Wh/mi or 47.2Wh/km) (34.7% lower)
4th 17.0A @ 122.5V (42kph, 79.8Wh/mi or 49.6Wh/km) (29.6% lower)
3rd 19.7A @ 120.0V (42.5-43kph, 89.6Wh/mi or 55.6Wh/km) (29.0% lower)
2nd 22.4A @ 120.0V (39.5-40kph, 108.2Wh/mi or 67.2Wh/km) (28.9% lower)
1st 37.7A @ 118.0V (39kph, 183.7Wh/mi or 114.1Wh/km) (24.9% lower)

So, going to the [GM Synchrmesh] fluid definitely seems like a step in the
right direction, however, not nearly as large a step as is required

On the plus side, the 3rd-2nd downshift "crunch" is gone, which had been
one of the touted benefits of using this tranny fluid.

So, some progress, but the hunt for better efficiency continues...

Cheers,

Roger.

---

Just a note: the energy savings seen from the less viscous gear oil doesn't translate directly to an equal decrease in total fuel consumption (or electricity use, in this case). Only the energy difference required to spin the wheels on jack stands was measured - not the total difference to actually drive the vehicle (with all its other associated losses factored in).

AndyH
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Re: Factory Maintenance Schedule-Ideas?

Thu Jan 13, 2011 2:36 pm

Engine, transmission, and differential fluid viscosity has been dropping for years as automakers work to increase fuel economy.

Synchromesh fluid is much lower viscosity than 80W-90 gear lube. Roughly, in engine oil terms, 80-90 is 40 or 50 engine oil while Synchromesh is 5W-30.

Synchromesh was formulated to replace 5W-30 engine oil in GM and Chrysler transmissions originally designed to use engine oil.

The search for efficiency is alive and well in the VW diesel community - I can confirm that Prius owners aren't the only hypermilers! ;)

From March 2006: http://forums.tdiclub.com/showpost.php? ... tcount=103
I posted a more appropriate overview on Ecomodder in early 2009:
http://ecomodder.com/forum/99592-post20.html
I pulled this together for a VW TDI forum. Last update was Oct '07. Most data comes from manufacturer spec sheets, but has been validated and/or expanded with oil analysis. Sorry...it's heavily weighted to Euro and VW fluids.

There's been a steady shift from 80-90 gear lubes to fluids that are basically automatic transmission fluid with some extreme pressure additives in order to improve corporate average fuel economy...so manufacturers can sell more trucks... You can see that the lightest fluids are off the chart...

When it comes to improving fuel economy thru changing fluids, the differential is the largest factor, with tranny second and engine last.

Changing from petroleum to synthetic - even with the same viscosity - can make a significant difference. For example - a class 8 truck (semi) tractor with dual drive axles, when moving from petroleum fluids to real synthetics, can gain 8.3%. 5.25% is the differentials, about .5% is the engine.

I did some highway testing with my old VW diesel - moving from the factory 75W-90 synthetic, to a synthetic synchromesh fluid, down to VW G52, and back up. The move from 75W-90 to the really thin G52 was worth 1.8mpg. In the end I moved back to 75W-90 to keep my 390,000 mile transmission a bit happier.

VI is viscosity index and speaks to viscosity stability as temperatures change. Higher is more resistant to change with temperature.

Transmission fluid viscosity is normally rated at 40C, while engine oils are rated at 100C. And, as already pointed out, the viscosity scales for gear oil and engine oils are different.

Viscosities are in cSt - centistokes - and are essentially a timed flow thru a cup with a hole in it.

(Manual Tranny Fluids)

VI Vis@40C Vis@100C
128 159.0 18.3 = AMSOIL CTL SAE 50 Powershift GL-1
..............16.7 = Motul MOTYLGEAR 75-90 GL-4/-5
..............15.6 = VW G50/G51 GL-4
185 90.0 15.6 = Redline MT-90 75-90 GL-4
..............15.2 = Mobil 1 Synthetic 75W-90 GL-5
..............15.2 = Motul Gear 300 75-90 GL-4/-5
..............15.0 = Elf Tranself Synthese FE 75-90 GL-4/-5
132 116.0 14.9 = AMSOIL AGL 80W-90 GL-5
177 84.5 14.7 = AMSOIL MTG 75-90 GL-4
..... 76.6 14.2 = VW G052-911
133 76.2 11.0 = AMSOIL CTJ SAE 30 Powershift GL-1
183 56.2 10.6 = Redline MTL 70-80 GL-4
194 47.1 9.6 = AMSOIL MTF Synchromesh Trans fluid (GM/Chrysler) GL-?
208 41.6 9.1 = Penzoil Synchromesh trans fluid GL-?
198 34.0 7.5 = Redline D4 ATF Dexron III / Mercon / API GL-4
138 40.5 7.1 = AMSOIL CTG SAE 10W Powershift GL-1
..... 31.2 6.5 = VW G-052-171-A2 GL-?
..... 35.1 6.4 = VW G-055-726-A2 GL-?
..............6.3 = VW G52 (part numbers G052726A2 / G05272601) GL-?

(Automatic Tranny Fluids - except for Redline D4 dual-use)

VI Vis@40C Vis@100C
.............8.3 = Honda CVT Fluid
.............7.6 = Mobil 1 Synthetic ATF
198 33.5 7.5 = Redline D4 ATF Dexron III / Mercon / API GL-4
.............7.4 = Mobil 1 Synthetic Dexron/Mercon
197 32.5 7.2 = Redline Synthetic ATF Dexron II / Mercon
.............7.1 = Mobil 1 Synthetic Multi-vehicle ATF
138 40.5 7.1 = AMSOIL Ford type F auto trans fluid
168 37.4 6.8 = AMSOIL Automatic Transmission Fluid ATF
..........5.5-6 = Ford Mercon SP
I don't have tech data for Nissan Matic S yet. I've purchased a quart and have sent a sample to an oil testing lab. I'll report back when I have numbers.

Don't change the Leaf's fluid to ANYTHING ELSE for any reason until we know absolutely what the OEM fluid is and why it was selected. There's a LOT MORE to lubricant selection than just viscosity.

Andy

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Re: Factory Maintenance Schedule-Ideas?

Thu Jan 13, 2011 2:44 pm

THe point is about friction. Many automakers have the option of lower friction and higher quality synthetics but don't use them because of cost. Many EV converters change their gear oil to an appropriate better quality product designed for high rpm gear boxes and efficiency while not sacrificing protection. I would also wonder if the service manual call out different weight for various climates. Synthetic does not need the heat in cooler climates and the ice provides to thin and is more consistent. I used a very expensive gear oil in one of my EVs but I can't remember the brand. Anyone know the gear oil specs?

AndyH
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Re: Factory Maintenance Schedule-Ideas?

Thu Jan 13, 2011 3:08 pm

EVDRIVER wrote:THe point is about friction. Many automakers have the option of lower friction and higher quality synthetics but don't use them because of cost. Many EV converters change their gear oil to an appropriate better quality product designed for high rpm gear boxes and efficiency while not sacrificing protection. I would also wonder if the service manual call out different weight for various climates.
No. Nissan Matic Fluid S is supposed to be a synthetic fluid and is a lifetime fill. I'll know more when I get my lab report back.
EVDRIVER wrote:Synthetic does not need the heat in cooler climates and the ice provides to thin and is more consistent. I used a very expensive gear oil in one of my EVs but I can't remember the brand. Anyone know the gear oil specs?
AndyH wrote:I don't have tech data for Nissan Matic S yet. I've purchased a quart and have sent a sample to an oil testing lab. I'll report back when I have numbers.
EVDRIVER - I'm a reliability tech and have a business serving primarily commercial vehicle fleets - from cars/light trucks to class-8. I prefer long-life real synthetic fluids where they're best used, and recommend fluids and/or service intervals to improve reliability, service life, fuel economy when ever possible. Just so you know where I'm coming from. ;)

Yes - friction is a factor. But...lubricants are a highly-engineered chemical mix. The traditional thought - as expressed by the unscientific testimonial you posted (sorry, truth) - is that a thicker fluid wastes more energy than a thinner fluid, and that must mean that thinner is better.

Not necessarily.

Two fluids otherwise identical in every way including viscosity can have different friction and/or energy saving properties with the addition of a friction modifier additive. (I'm not talking any over the counter product - I'm talking about chemistry tweaks in the oil formulation - never add anything to a fully formulated oil!).

Fluids must do more than one function. They lubricate, protect from rust and corrosion, transfer heat to the outer case of the transmission. Oil does not compress. A thin layer of oil on gear teeth, for example, forms the 'pillow' that keeps gear teeth from physically touching. Thinner fluids cannot protect from wear as well as a thicker fluid. Just one example.

Fluid choice includes a LOT of trade-offs.

For the Leaf - the gearbox uses Nissan's latest (and lightest) automatic transmission fluid. Don't change it to anything lighter (provided we can find anything thinner!) to chase economy - driving style and tire inflation will give us much larger performance gains with no potential down-side risk.

Andy

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Re: Factory Maintenance Schedule-Ideas?

Mon Jan 24, 2011 6:34 pm

I just wanted to follow up on the brake fluid maintenance requirement that was brought up earlier (obviously it's still bugging me).

I downloaded another Nissan maintenance schedule and I was surprised that I did not see the brake fluid change in that current maintenance schedule. I wonder why that is. I also noticed that the gasoline cars have the same maintenance schedule guidelines (schedule 1 or 2). I can understand why short trips are bad for gasoline cars. The engine warm up time, friction before fluids are circulated, etc. But I don't understand why short trips are so bad for EV's. Since I do drive a short ways to my job I guess I am in schedule 1 and still can't believe that we need to do annual brake fluid changes.

Why would the LEAF need this but not other Nissan cars? Did they use a different system that is not as air tight and can take on more moisture? Just bugging me that the LEAF has EXTRA maintenance that other Nissan's are not required to do. One of the big things with the LEAF was not having to do annual fluid changes, etc. Well I'll stop complaining now.

-Peter

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Re: Factory Maintenance Schedule-Ideas?

Mon Jan 24, 2011 6:53 pm

AndyH wrote:
EVDRIVER wrote:THe point is about friction. Many automakers have the option of lower friction and higher quality synthetics but don't use them because of cost. Many EV converters change their gear oil to an appropriate better quality product designed for high rpm gear boxes and efficiency while not sacrificing protection. I would also wonder if the service manual call out different weight for various climates.
No. Nissan Matic Fluid S is supposed to be a synthetic fluid and is a lifetime fill. I'll know more when I get my lab report back.
EVDRIVER wrote:Synthetic does not need the heat in cooler climates and the ice provides to thin and is more consistent. I used a very expensive gear oil in one of my EVs but I can't remember the brand. Anyone know the gear oil specs?
AndyH wrote:I don't have tech data for Nissan Matic S yet. I've purchased a quart and have sent a sample to an oil testing lab. I'll report back when I have numbers.
EVDRIVER - I'm a reliability tech and have a business serving primarily commercial vehicle fleets - from cars/light trucks to class-8. I prefer long-life real synthetic fluids where they're best used, and recommend fluids and/or service intervals to improve reliability, service life, fuel economy when ever possible. Just so you know where I'm coming from. ;)

Yes - friction is a factor. But...lubricants are a highly-engineered chemical mix. The traditional thought - as expressed by the unscientific testimonial you posted (sorry, truth) - is that a thicker fluid wastes more energy than a thinner fluid, and that must mean that thinner is better.

Not necessarily.

Two fluids otherwise identical in every way including viscosity can have different friction and/or energy saving properties with the addition of a friction modifier additive. (I'm not talking any over the counter product - I'm talking about chemistry tweaks in the oil formulation - never add anything to a fully formulated oil!).

Fluids must do more than one function. They lubricate, protect from rust and corrosion, transfer heat to the outer case of the transmission. Oil does not compress. A thin layer of oil on gear teeth, for example, forms the 'pillow' that keeps gear teeth from physically touching. Thinner fluids cannot protect from wear as well as a thicker fluid. Just one example.

Fluid choice includes a LOT of trade-offs.

For the Leaf - the gearbox uses Nissan's latest (and lightest) automatic transmission fluid. Don't change it to anything lighter (provided we can find anything thinner!) to chase economy - driving style and tire inflation will give us much larger performance gains with no potential down-side risk.

Andy


Andy, I am well aware of the complexities and variables in fluids and their applications and even though you say "no" to my comment I never said the LEAF fluid was not the best application since I never stated I knew what it was and was wondering to see if there was a better option, no matter the viscosity or other merits. EV drives are also different than standard gear boxes as well. There are many EV builders that have done more detailed analysis on this I really did not see the need to go into technical detail on all the pros and cons since this is not a very tech forum and the point was simply to explore potential options and give some generic reasons why. I could also go into great detail for pages about parasitic loads in the drive, foaming, double-roling loads, details about all the regen misconceptions and other junk few would care to hear about or understand. Thank you for informing us about the exact fluid used in the LEAF, I don't think an chemical analysis is needed but some of these drives are shipped with fluids that can be upgraded to a worthwhile benefit with a quick check, not a lab analysis. It was simply something worth checking and I'm glad to looked it up on the LEAF specs for confirmation as I did not download that PDF, thank you.

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Re: Factory Maintenance Schedule-Ideas?

Mon Jan 24, 2011 6:55 pm

prberg wrote:I just wanted to follow up on the brake fluid maintenance requirement that was brought up earlier (obviously it's still bugging me).

I downloaded another Nissan maintenance schedule and I was surprised that I did not see the brake fluid change in that current maintenance schedule. I wonder why that is. I also noticed that the gasoline cars have the same maintenance schedule guidelines (schedule 1 or 2). I can understand why short trips are bad for gasoline cars. The engine warm up time, friction before fluids are circulated, etc. But I don't understand why short trips are so bad for EV's. Since I do drive a short ways to my job I guess I am in schedule 1 and still can't believe that we need to do annual brake fluid changes.

Why would the LEAF need this but not other Nissan cars? Did they use a different system that is not as air tight and can take on more moisture? Just bugging me that the LEAF has EXTRA maintenance that other Nissan's are not required to do. One of the big things with the LEAF was not having to do annual fluid changes, etc. Well I'll stop complaining now.

-Peter
You make a good point about severe driving and the Leaf. Off the top of my head (while wearing my reliability/lube tech/maintenance hat), it would appear that shorter trips would likely be on 'other than freeway/expressway/interstate' where there are plenty of stopping opportunities on a journey. I don't expect this to be harder on an EV than an ICE - at least for vehicles with similar weights and brake systems - but not necessarily mile for mile easier either.

From a warranty perspective, the 'severe service' guidelines may be heavily influenced by ICE experience and while maybe not as applicable to EVs, it's still the 'law of the land'.

The only other thought that pops in would require a side-by-side look at the different braking systems. We know from the service manuals that the Leaf has a very computerized braking system that mixes/matches friction and regen and ABS and traction control. Maybe Nissan wanted a little more of a brake fluid performance buffer. This is a guess and may not have anything to do with anything. :? ;)

AndyH
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Re: Factory Maintenance Schedule-Ideas?

Mon Jan 24, 2011 7:26 pm

EVDRIVER wrote:Andy, I am well aware of the complexities and variables in fluids and their applications and even though you say "no" to my comment I never said the LEAF fluid was not the best application since I never stated I knew what it was and was wondering to see if there was a better option, no matter the viscosity or other merits. EV drives are also different than standard gear boxes as well. There are many EV builders that have done more detailed analysis on this I really did not see the need to go into technical detail on all the pros and cons since this is not a very tech forum and the point was simply to explore potential options and give some generic reasons why. I could also go into great detail for pages about parasitic loads in the drive, foaming, double-roling loads, details about all the regen misconceptions and other junk few would care to hear about or understand. Thank you for informing us about the exact fluid used in the LEAF, I don't think an chemical analysis is needed but some of these drives are shipped with fluids that can be upgraded to a worthwhile benefit with a quick check, not a lab analysis. It was simply something worth checking and I'm glad to looked it up on the LEAF specs for confirmation as I did not download that PDF, thank you.
Sorry that our chat resulted in ruffled feathers - not intended. While you may feel comfortable digging into tribology and other fun areas, I have to come back to my recommendation - especially on a forum such as this - that one uses the recommended fluid.

Yes - I agree completely that there might be other fluids on the street that claim similar performance. And no doubt there will be folks that might believe that a different fluid might provide a range benefit.

You're quite right - an EV drive is not necessarily the same as a manual transmission...and may or may not more closely resemble aircraft gear reduction units with an integral differential. ;)

But speaking as someone with a business in high-end long-life synthetic fluids and fleet maintenance, and having worked with folks that test lubricants in an independent lab setting, and being one that highly values efficiency (but experiments with my own equipment before I'll risk another's equipment on a guess ;)), I know that at most a manual gearbox and transaxle on a front drive vehicle is only worth about 3% of the total losses in a system. The fixed-speed gear reduction/transaxle used on the Leaf likely accounts for less - closer to 1.5%.

The gearbox is already using a low-viscosity synthetic product. There are few automatic transmission fluids on the market with a lower viscosity. The possibility that a fluid change will have a measurable affect on range is very, very low. The possibility that a fluid change may lead to some harm is very low but higher than any gains.

Look at it this way - if the gearbox is responsible for 1.5% of energy loss, and we find a super light magic fluid that removes 100% of the losses, it'll be worth at most 1.5 miles additional range on a 100 mile drive.

The likelihood of increased wear due to the lower viscosity fluid's lower film strength, and the resulting geometric progression of wear due to new metal particles being circulated, will be much more noticeable than the range improvements.

In my opinion, the potential downside is much greater than the potential gain.

Believe me - I'd like to use my company's products in my Leaf when it arrives. :D But the only things I would consider changing from the start is coolant and brake fluid. Maybe later I'll find something that provides lower wear than Nissan Matic Fluid S, but I'm not touching it until I have an oil sampling history from my gearbox, and not until I get the lab results back from the quart of Nissan fluid I bought.

All that aside, EVDRIVER, the LAST thing I'm going to do is to tell anyone what to do. I have enough trouble controlling my own life - I'm not on the planet to try to control anyone elses. :lol: Do what you want to do. And if you do, let me know - I'll send oil sample kits. ;)

Andy

wgs1912
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Re: Factory Maintenance Schedule-Ideas?

Wed Jan 26, 2011 9:20 pm

Andy just for referance matic S is a new fluid for nissan. It's first use was in the 2009 370Z when it came out.
Is it better to let people think you are stupid than open your mouth and prove it?

AndyH
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Re: Factory Maintenance Schedule-Ideas?

Wed Jan 26, 2011 9:37 pm

wgs1912 wrote:Andy just for referance matic S is a new fluid for nissan. It's first use was in the 2009 370Z when it came out.
Thanks for that! I understand it's also replacing Matic J in other cars as well. Does that sound accurate to you?

I've been studying (and selling) lubes since 2001, but most of my in-depth knowledge and experience is with US and Euro lubes - I'm not fluent in Japanese OEM specs.

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