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?
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?