Motul Gear 300 & HPL Differential Life 75W90 VOA comparison!

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So, as everyone knows from my past posts, I am a big fan of Motul's Gear 300 especially in Subaru differentials. It's the only gear lube I've ever personally used in my 6 Subarus, and it's what I use for all friends and family as well. Its claimed specs are very good; a full synthetic formulation and esters are in play as well. However, I've never personally done a VOA or UOA on it, and many board members have questioned just "how good" it is.

I decided, along with a competitor's product, (@High Performance Lubricants) to send out a sample of both 75w90s for testing. The interesting and comforting thing I immediately saw from the Motul is that the gear oil is literally within fractions of a percent on all its TDS specifications (in red box)! Obviously, I wanted to engage Dave's expertise on fully deciphering what the test results tell us, not only about the Motul, but also how it compares to HPL. My amateur translation of the data:

- Motul is a very good, top tier gear lube. It is significantly thinner than the HPL but still in grade. The 40*C & 100*C viscosities are spot on to the PDS, and VI tested a hair better because of the slightly lower 40*C viscosity.

- The high density of the Motul shows a significant ester content, but the higher Brookfield numbers on the Motul shows that the overall oil is made with slightly lower quality components than the HPL- even though the measured viscosity is much lower, the cP @ -40*C is higher, indicating the Motul is harder to circulate with the paddle in the test.

- Pour points & flash points are essentially identical due to the resolution of the test methods (-80+*F for both oils!).

- 4-ball wear tests are also essentially identical, but the HPL can carry an additional 100kg load on the 4-Ball Weld test before failure, even though the Motul result is a good result.

- KRL is a shear stability test which will destroy any VIIs in an oil, and show the impact on viscosity loss as the oil is in use; here both the Motul and HPL deliver admirable results, showing less than 1.4% shear during the test, and their post-test viscosities are very similar to the virgin oil.

My overall takeaways: The Motul Gear 300 is definitely a great product and is exactly what Motul says it is. Full synthetic, ester-based, and extremely low shear. If you're using it currently like I am, or are intending to purchase it, rest assured that it will work well if it's what your diffs require. HPL's 75w90 is a little thicker, but has better Brookfield results and a 25% higher weld safety level, along with delivering a very shear-stable product.

Anyways, sorry for the long post but this has been on my plate for a long time to quantify how good the Motul product is since I've been using and recommending it for years. However, I will be switching to the Differential Life from now on since there are some better characteristics, and HPL is US-owned and based!
@dnewton3 do you have anything to add, since I know this info is right up your alley?

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I would consider these two to be the only two that are sure to be formulated with appropriate FM for synchronized transmissions and to have a GL-5 rating for the hypoid differential.
I would concur. That's one of the things I forgot to mention since it's unfortunately been about 4 years since I've owned a Subie with a manual trans.
 
Well, with a little bit of patience we will be releasing the data on this series which is called Differential Life cold climate. This slipped out. It will be added to the webstore as well. These are PAO and No VII.
Oops… sorry Dave. Looks like it will generate some additional sales though! 😎
 
So, as everyone knows from my past posts, I am a big fan of Motul's Gear 300 especially in Subaru differentials. It's the only gear lube I've ever personally used in my 6 Subarus, and it's what I use for all friends and family as well. Its claimed specs are very good; a full synthetic formulation and esters are in play as well. However, I've never personally done a VOA or UOA on it, and many board members have questioned just "how good" it is.

I decided, along with a competitor's product, (@High Performance Lubricants) to send out a sample of both 75w90s for testing. The interesting and comforting thing I immediately saw from the Motul is that the gear oil is literally within fractions of a percent on all its TDS specifications (in red box)! Obviously, I wanted to engage Dave's expertise on fully deciphering what the test results tell us, not only about the Motul, but also how it compares to HPL. My amateur translation of the data:

- Motul is a very good, top tier gear lube. It is significantly thinner than the HPL but still in grade. The 40*C & 100*C viscosities are spot on to the PDS, and VI tested a hair better because of the slightly lower 40*C viscosity.

- The high density of the Motul shows a significant ester content, but the higher Brookfield numbers on the Motul shows that the overall oil is made with slightly lower quality components than the HPL- even though the measured viscosity is much lower, the cP @ -40*C is higher, indicating the Motul is harder to circulate with the paddle in the test.

- Pour points & flash points are essentially identical due to the resolution of the test methods (-80+*F for both oils!).

- 4-ball wear tests are also essentially identical, but the HPL can carry an additional 100kg load on the 4-Ball Weld test before failure, even though the Motul result is a good result.

- KRL is a shear stability test which will destroy any VIIs in an oil, and show the impact on viscosity loss as the oil is in use; here both the Motul and HPL deliver admirable results, showing less than 1.4% shear during the test, and their post-test viscosities are very similar to the virgin oil.

My overall takeaways: The Motul Gear 300 is definitely a great product and is exactly what Motul says it is. Full synthetic, ester-based, and extremely low shear. If you're using it currently like I am, or are intending to purchase it, rest assured that it will work well if it's what your diffs require. HPL's 75w90 is a little thicker, but has better Brookfield results and a 25% higher weld safety level, along with delivering a very shear-stable product.

Anyways, sorry for the long post but this has been on my plate for a long time to quantify how good the Motul product is since I've been using and recommending it for years. However, I will be switching to the Differential Life from now on since there are some better characteristics, and HPL is US-owned and based!
@dnewton3 do you have anything to add, since I know this info is right up your alley?

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Thanks for going all out on this. Good write up too. I try to have a few brands I use their stuff.
 
Well, with a little bit of patience we will be releasing the data on this series which is called Differential Life cold climate. This slipped out. It will be added to the webstore as well. These are PAO and No VII.
Gonna have a drop or two of ester to counteract the PAO? That was my worry when I bought 50 quarts of Redline CVT and it was worded as PAO until I called and got a more down to reality answer. How low is this Differential Life Cold going to flow to? Remember being in Billings,MT one winter and all the guys jack up the rear tires slightly and let them run all night long.
 
@SubieRubyRoo what lab did this testing? I wasn’t familiar with PDSC, had to look it up. That was the most different result between the 2 lubes…other than viscosity. I presume bigger number is better??? It would be super awesome if we could get apples to apples testing of Redline and Amsoil Severe Gear along with these 2. I’d chip in…I think, though I don’t have either fluid. Of course, being totally selfish, I’d love to see how Ford’s 75w85 stacks up as well. For that, I can provide a sample, I think.

@High Performance Lubricants I don’t know enough about viscosities, but would your Diff Life be “too thick“ for a full-size Ford Transit van with 9.75 rear diff which has 75w85 spec’d? I was thinking the Motul might be the closest to 75w85 of all the common 75w90’s out there. (Yes, I know Redline makes a 75w85). HPL lube appears a bit “thick” 😉

also, Eaton makes a drop-in TruTrac Torsen limited slip for that 9.75 that I am strongly considering. Eaton advises against synthetic lubes (I know, sounds like dark-ages thinking), but I am presuming again that is because most synthetic gear lubes nowadays say they have friction modifiers (Eaton also says no to FM’s in mineral oil versions too, claiming it messes with the limited slip “bias,” making it less effective. Motul gear 300 was one exception (no FM’s in the ”normal version”…that and the Delvac, one version of the Redline, maybe the “non-Severe” Gear Amsoil, and maybe a Supertech. All without FM’s. I think HPL has FM added, as does the SevereGear. Any thoughts on this, Dave?

@Brian553 what is your experience with Subaru turbo 5-speed stick shifts? While I firmly believe Dave’s claim the HPL is tippy-top shelf gear lube, that doesn’t mean it’s right for the older Subaru performance stick shifts. That said, I would love someone’s hands on experience in that trans. I own one such older Subaru Turbo stick shift. Someday soon, I need to replace the fluid. Motul works, though Motul with Redline Lightweight Shockproof 50/50 mix works even better, at least in N. Texas. (in the 5-speed…don’t do this in the 6-speeds from what I’ve been told; BTW, this is not the infamous Uncle Scotty’s frankenbrew. Anyway, whoever dissed “forum mixes” be careful, there were good ones and bad ones, and 6-speeds are very different internally from the 5-speeds…lubrication-wise…I presume better). Apparently, mine was the good mix For a 5-sp. Dramatically better than whatever the dealer put in…assuming Subaru Extra S, though not sure).
 
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@Brian553 what is your experience with Subaru turbo 5-speed stick shifts? While I firmly believe Dave’s claim the HPL is tippy-top shelf gear lube, that doesn’t mean it’s right for the older Subaru performance stick shifts. That said, I would love someone’s hands on experience in that trans. I own one such older Subaru Turbo stick shift. Someday soon, I need to replace the fluid. Motul works, though Motul with Redline Lightweight Shockproof 50/50 mix works even better, at least in N. Texas. (in the 5-speed…don’t do this in the 6-speeds from what I’ve been told; BTW, this is not the infamous Uncle Scotty’s frankenbrew. Anyway, whoever dissed “forum mixes” be careful, there were good ones and bad ones, and 6-speeds are very different internally from the 5-speeds…lubrication-wise…I presume better). Apparently, mine was the good mix For a 5-sp. Dramatically better than whatever the dealer put in…assuming Subaru Extra S, though not sure).
I've owned a 2012 WRX for about 4 years before my BITOG days. Now I own a '14 Forester 6MT. I wasn't partial to the NASIOC mixes given the plethora of unknowns left out, and I feel I am getting my money's worth with either of these two products. HPL will answer your fitment concerns--I don't forsee any.
 
@SubieRubyRoo what lab did this testing? I wasn’t familiar with PDSC, had to look it up. That was the most different result between the 2 lubes…other than viscosity. I presume bigger number is better??? It would be super awesome if we could get apples to apples testing of Redline and Amsoil Severe Gear along with these 2. I’d chip in…I think, though I don’t have either fluid. Of course, being totally selfish, I’d love to see how Ford’s 75w85 stacks up as well. For that, I can provide a sample, I think.

@High Performance Lubricants I don’t know enough about viscosities, but would your Diff Life be “too thick“ for a full-size Ford Transit van with 9.75 rear diff which has 75w85 spec’d? I was thinking the Motul might be the closest to 75w85 of all the common 75w90’s out there. (Yes, I know Redline makes a 75w85). HPL lube appears a bit “thick” 😉

also, Eaton makes a drop-in TruTrac Torsen limited slip for that 9.75 that I am strongly considering. Eaton advises against synthetic lubes (I know, sounds like dark-ages thinking), but I am presuming again that is because most synthetic gear lubes nowadays say they have friction modifiers (Eaton also says no to FM’s in mineral oil versions too, claiming it messes with the limited slip “bias,” making it less effective. Motul gear 300 was one exception (no FM’s in the ”normal version”…that and the Delvac, one version of the Redline, maybe the “non-Severe” Gear Amsoil, and maybe a Supertech. All without FM’s. I think HPL has FM added, as does the SevereGear. Any thoughts on this, Dave?

@Brian553 what is your experience with Subaru turbo 5-speed stick shifts? While I firmly believe Dave’s claim the HPL is tippy-top shelf gear lube, that doesn’t mean it’s right for the older Subaru performance stick shifts. That said, I would love someone’s hands on experience in that trans. I own one such older Subaru Turbo stick shift. Someday soon, I need to replace the fluid. Motul works, though Motul with Redline Lightweight Shockproof 50/50 mix works even better, at least in N. Texas. (in the 5-speed…don’t do this in the 6-speeds from what I’ve been told; BTW, this is not the infamous Uncle Scotty’s frankenbrew. Anyway, whoever dissed “forum mixes” be careful, there were good ones and bad ones, and 6-speeds are very different internally from the 5-speeds…lubrication-wise…I presume better). Apparently, mine was the good mix For a 5-sp. Dramatically better than whatever the dealer put in…assuming Subaru Extra S, though not sure).
Which Redline and Severe Gear viscosity? I have the Amsoil SG 75w90 & 75w110 on my shelf, so if you wanted to buy and mail me a quart of your flavor of Redline (unopened, of course), I would get the testing done for both.
 
Which Redline and Severe Gear viscosity? I have the Amsoil SG 75w90 & 75w110 on my shelf, so if you wanted to buy and mail me a quart of your flavor of Redline (unopened, of course), I would get the testing done for both.
I don’t have any Redline 75w90, however I do have a sample of their lightweight shockproof…which, well, I have no idea how that would test, since I used it as an “additive.“. I assume there is more interest in “traditional” Redline 75w90.

I also have some Ford Motorcraft 75w85, which may benefit anyone with a 8 yr old or less Ford (or Lincoln) truck.

I can send either or both. But does anyone else care to see these? (Heh, does anyone know where to get some cheap bottles?). How many oz’s do you need? These would both be from opened bottles, leftover, sitting on a shelf for quite some time (2 yrs for Ford 75w85, maybe 5 yrs for the Shockproof)

regarding Severe Gear, personally I would want to see the 75w90, which I assume is more like the Motul and/or HPL, but the “thickie” people might want to see the 110 weight. Any opinions?
 
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I've owned a 2012 WRX for about 4 years before my BITOG days. Now I own a '14 Forester 6MT. I wasn't partial to the NASIOC mixes given the plethora of unknowns left out, and I feel I am getting my money's worth with either of these two products. HPL will answer your fitment concerns--I don't forsee any.
I think both the Subie’s you mention are the newer design that don’t need the “extra help” the older 5-sp needed, so I agree, my mix would not appeal to you. i’ll go out on a limb here and say the HD 5-sp relied more on “splash” lubrication, whereas the newer WRX had a pump of some sort??? Or narrow galleys maybe??? I don’t know which the Forrester 6-sp is closer in design to: the hi-perf 6-sp, or the hi-perf HD 5-sp…or maybe neither. I was aware of the “mix” controversies when I put my mix in, and can assure you I was hesitant too, but have been impressed…but this applies only to the hi-perf 5-speed…such as found in 2004-2009 Outback XT and Legacy GT (other than Spec B…which had the hi-perf 6-sp). I don’t know which “Impreza-based“ models got that 6-speed, maybe only the STI, nor which Imprezas, if any, got the HD 5-sp, but I’m way too far OT and in the weeds. I will probably put the same mix in again,..unless Motul Gear 300 is gone from our market, or Redline deletes the Shockproof from their lineup…in which case I will strongly consider the HPL. As crusty as his opinions were, I learned “BAC5.2“ on those forums had some good advice for souping up Foresters, Outback XT’s and LGT’s.

Closing out the Susie talk…unless someone wants to further beat that horse. but that leaves my Ford diff questions for HPL response.
 
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I don’t have any Redline 75w90, however I do have a sample of their lightweight shockproof…which, well, I have no idea how that would test, since I used it as an “additive.“. I assume there is more interest in “traditional” Redline 75w90.

I also have some Ford Motorcraft 75w85, which may benefit anyone with a 8 yr old or less Ford (or Lincoln) truck.

I can send either or both. But does anyone else care to see these? (Heh, does anyone know where to get some cheap bottles?). How many oz’s do you need? These would both be ~5 yr old samples, opened, leftover, sitting on a shelf for quite some time.

regarding Severe Gear, personally I would want to see the 75w90, which I assume is more like the Motul and/or HPL, but the “thickie” people might want to see the 110 weight. Any opinions?
The lab said the safest way to ensure all the tests could be run (or re-run from the same sample if needed for verification) was to send a full quart. So that’s what I did. There are a couple things I’m passionate enough about for the board to drop this kind of coin without ever getting the benefit (several virgin filter C&Ps and a bunch of different VOAs), so if you or anyone else want to ship a quart of Redline 75w90 to me for comparison testing with the Amsoil & compare to the Motul & HPL I’d be happy to get it all done.
 
I probably better just offer money then, say $20 😬. You’ll need some extra donors then. I’m open to that $20 going for Motorcraft 75w85 or Amsoil SG 75w90.

if they need a quart, i‘m guessing this isn’t a $35-$40 analysis. 🥴
 
There is a 75w85 and more in the series about to be released. Our oils have the limited slip additive included, however we can certainly make it without the additive. I think it’s fair to say that us, Motul, Redline, and Amsoil all make very good gear oils. It is probably also fair to say that each company has a slightly different approach to their respective products.
 
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