It is a very good choice for oil in a motorcycle with wet clutch, with no friction modifiers and strong additive package with plenty of Zinc/Phosphorous for protection of the engine against wear. Being a high quality synthetic, it should hold up better/longer than mineral-based motorcycle oils which I see as usually overpriced for what you get.
Many folks opt for the diesel-rated 5W-40 synthetics and 15W-40 conventionals and get great or acceptable service from these oils at a lower price point. A big part of how well an oil does in a combined engine/trans bike is how well it shifts with an oil and how long it continues to shift acceptably. Some people will also send a sample of used oil to the lab to see how well it held up chemically, and to quantify the wear metals/fuel dilution while using a particular oil.
M1 4T is a good choice. Amsoil and Redline make some good synthetic motorcycle oils that are popular. Spectro and Motul make some good stuff as well.
I've used Mobil 4T before -- good oil. Just a bit hard to find where I live. My local Auto Zone and Checkers carry it, but rarely had more than a bottle or two on the shelves. My local Wal-Mart used to carry it, but no longer does.
My bike (Goldwing) has a wet clutch and shared sump design, but otherwise it's an Accord engine -- in other words, a relative pussycat on oil. Rotella 15W-40 works perfectly well for me, as evidenced by UOAs (see here).
I've used it for 20,000 of my bike's 40,000 miles with no problems. I use the 20w50 weight since my bike is air cooled and it gets pretty hot down here. The formulations are about the same except for the viscosity. The 20w50 is on the thick side of the 50 weight and the 10w40 is on the thin side of the 40 weight. I would go with the 10w40 in a water cooled bike. There is a very informative motorcycle oil white paper on the amsoil website. Both of the Mobil 1 oils are compared with amsoil motorcycle oils and several other brands. Both of the Mobil 1 oils do very well. Use with confidence.
Originally Posted By: chestermo
There is a very informative motorcycle oil white paper on the amsoil website. Both of the Mobil 1 oils are compared with amsoil motorcycle oils and several other brands. Both of the Mobil 1 oils do very well.
If I recall correctly, the comparison was essentially a dead heat between Amsoil and Mobil 1 except for the foaming test, where they showed Amsoil having lower foaming tendencies than Mobil 1. But the difference was slight.