Gear oil

Posted this in the 308/28 section in a thread debating gear oil, but thought it good to put this in our section as well. This is the best explanation of the GL4 verses 5 debate at the core of which is the best gear oil for our V8 transaxles, in my case a 1988 Mondial 3.2 Cab.

I have had the best shift experience with Redline MTL, second best with Redline 75W90NS, and recently tried the Amsoil Severe Gear 75W90, with a stiff second gear change outcome at lower temperatures. Back to the Redline MTL for me, especially since I drive in the spring and fall shoulder driving seasons in Toronto, Canada with near freezing temperatures.

The paper attached would also suggest the MTL or MT90 if you wanted the OEM spec viscosity would be the most suitable chemistry.
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You need to read the debate on the 308/28 thread. The gist of it is that many of the recommendations on modern oils appear to stay aligned with the original OEM ratings even though the chemistry and additive packages have long since changed. Even the Agip brand, now Eni, has superceded its original formulations twice (SX became LSX became SX/S), with chemistry that is not the same as the OEM spec.

Many have had good experience with Redline 75W90NS, but also with MTL solving for some with no apparent downside, and some of the most experienced mechanics on Fchat go with the MTL.

Simply noting that after having reflected on all the facts and commentary I have seen over the years, and experimented myself, that the MTL offers the best shift quality, and as a modern GL4 should in fact represent the ideal chemistry for our cars. Also, check the prices of syncros, and a product that favours the longevity of those (and a better shift enjoyment experience), that works for me even if there are other tradeoffs, indeed none which have been identified.