I bit the bullet as the guinea pig and wanted to give some feedback on the Ravenol full synthetic T-IV transmission fluid. I have only completed 1,200 miles on the new fluid. I currently have 138k miles on my XC90 and previously did two fluid changes using Mobil 3309 since ~88k miles; an average 25k miles the past two changes. When switching to Ravenol in this 3rd fluid change, the 2nd set of Mobil JWS 3309 fluid still looked good with close to 30k miles. I do a lot of highway driving across the country and probably could have gone another 5-10k miles.
When pouring the Ravenol, I noticed the synthetic has a lower viscosity when cold. I had some fresh Mobil 3309 I kept for leveling the fluid in the past and did a direct comparison. One for the Ravenol for having better cold flow.
The shifting was good before, but the shifting has improved! The shifts are smoother yet crisper, feels like a new transmission. Overall, the transmission is more consistent when just starting to drive to when it is 90F+ outside stuck in traffic. Torque converter lock-up is better too. My initial personal opinion is it's a better fluid than the Mobil, but it should be.
The take away
The price seems high, but I probably will get more consistency in driving through varying temperatures and through the life of the fluid as well as I (hope) to get more life out of the transmission. The fluid may last twice as long, but I am guessing I can get 50% more out of the fluid instead of additional 100% because I would want to change it early due to friction disc material floating around. As I did almost 30k miles in the last 12 months, the extra life is better for me.
One thing to consider is the shear rating and how mineral oil shears down its hot temp viscosity over time (gets thinner over time at operating temp). Tim Thurber did an oil analysis and his factory JWS 3309 (T-IV) fluid came back with the hot temp viscosity (@100C) closer to thinner WS transmission fluid spec for 2011+ XC90s. So, all of you with old transmission fluid are running a thinner fluid at operating temp. Synthetic fluid keeps that operating temp viscosity more consistent for the life of the fluid. People who have tested Dexron III (mineral) vs Dexron VI (synthetic) have seen better operating temp viscosity with Dex VI synthetic. These types of results shouldn't be a surprise because it is similar to conventional vs synthetic engine oil.
So, better cold flow, better hot temp viscosity, more consistency, better shifting, better torque converter lock-up, and longer life. Well worth the switch to Ravenol full synthetic. My only suggestion is to do an initial change from factory fluid with Mobil 3309 or similar (to remove as much floating friction material, carbon, etc.) and then on the 2nd fluid change go for Ravenol.
I will update as I put on more miles.
Links and references:
https://www.amazon.com/dp/B01NBP64PG...ing=UTF8&psc=1 Ravenol on Amazon (sold by Blauparts).
https://www.youtube.com/watch?v=Xl8AfrRcJY4 Interesting video of hot testing Ravenol full synthetic. Transmission fluid is already much thinner than engine oils. Amazing how well it performs and doesn't carbon up.
https://www.youtube.com/watch?v=USRsFf5ZQys Flow/viscosity testing at 3 yrs of use. The old fluid flows better than new, but that could be for many reasons like it has more friction material (denser), less friction modifiers, etc. The video does show how well it still flows when cold.
http://www.timthurber.com/volvo-xc90...-80sc-6-speed/ Tim Thurber's page on changing transmission fluid.