JohnnyGrey, I see you just bought Mobil 1 ATF ... which seems to be working good. I am not surprised by your increased mileage numbers ... Mobil 1 products are formulated to be a tick thinner than other brands right out of the bottle. That's part of the reason people get such a good 'seat-of-the-pants dyno' result.
But, if you are looking to protect your tranny, I'd consider Royal Purple Synchromax. I'm generally not a big fan of their products, but I don't know of another purpose-made synchromesh fluid that is formulated as thin as (specified) ATF ... about 6.0 to 7.5 cSt.
It may even get rid of the howl as it has a better additive package for protecting against metal-to-metal contact.
There are the GM/Pennzoil syncromesh fluids ... but they are heavier at around 8.5 to 9.5 cSt viscosity. Again, one of these may get rid of your howl ... but at a cost of higher resistance (hydrodynamic drag).
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--- Bror Jace
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