Mobil 1 15W50 motorcycle oil??

[petermm]

I read that some of you use Mobil 1 15W-5050 and thought that it would be a good combination of high quality synthetic and not to thin oil.
I therefore asked my local Mobil outlet to get me 12 liters.
What I got is Mobil 1 Racing 4T that according to the backside is ?very high performance fully synthetic oil for all types of high-powered 4-stroke MOTOECYLE engines?.
Is that the Mobil 1 15W-50 that you use?
Should I use it in my TwinCam?

[marcfuller]

I encourage you to use the MX4T. It is a much better choice for our vintage high performance flat tappet engines than the current API SM grade specification automobile engine oils (even Mobil 1).

This was not a consideration until the last 3 years or so. To reduce auto emissions and enhance the life span of catalytic converters the zinc-phosphorus (ZDDP) (which is a very good high pressure lubricant) content of automobile oils has been significantly reduced. This is acceptable since most US cars for the last 6-8 years have used roller tappets and therefore do not have the tappet loads of our TwinCams.

Here is what Mobil One says is the main difference between their motorcycle and automobile oils-

"It's a little hard to generalize about the difference between Mobil 1 passenger-car motor oils and Mobil 1 motorcycle oils. That's because not all viscosities of Mobil 1 passenger-car oils have the same levels of zinc and phosphorus, and there are even greater differences among the three Mobil 1 motorcycle oils. In general, Mobil 1 motorcycle oils have:
Additive packages balanced differently for motorcycle engine and transmission operation. For passenger vehicles, fuel economy and emission system protection are higher priorities. These require low phosphorus systems and the use of friction modifiers. "

As to the advantage of Mobil 1 motorcycle oil-

In addition to the overall benefits listed above specifically, high-temperature stability and low volatility/low oil consumption Mobil 1 synthetic motorcycle oils also offer superior anti-corrosion performance compared to conventional motor oil, which is important in many parts of the country where bikes may sit in garages for several months of the year.

Compared to conventional oils, Mobil 1 motorcycle oils provide superior wear and high-temperature protection, and promote engine cleanliness and lower oil consumption. [/list]

And as to the specific the traits of MX4T-

Mobil 1 MX4T is designed for sport bikes. Most of these bikes have multi-cylinder/multi-valve engines and use a common sump, which means the engine oil lubricates the engine, transmission and wet clutch. So unlike Mobil 1 for cars, Mobil 1 MX4T has no friction modifiers, which could lead to clutch slippage.

The motorcycle oil also has more phosphorus/zinc for enhanced wear protection at high engine speeds and high loads.

In addition, Mobil 1 MX4T uses different dispersant/detergent technology for better high-temperature performance and engine cleanliness. Mobil 1 MX4T is also offered in a different viscosity grade than Mobil 1 for passenger cars.

All that said - MX4T is pricey, and you can get very similar performance and ZDDP levels from automobile synthetic racing oils (my choice is Pennzoil Synthetic Racing 20-50) with a little lower price, and conventional diesel engine oils such as Shell Rotella with a much lower price.

In any case I would not use a current SM grade automobile oil in a TwinCam, regardless of the oil being synthetic or conventional.